Let's get something straight right off the bat, "London broil" isn't a cut of beef. It's a method. Technically, it refers to a marinated, broiled (or grilled) flank steak sliced thin against the grain.
But over the decades, the term has become so tangled up with a specific cut that most grocery stores label top round, flank, or even coulotte as "London broil." Whatever cut you grab, one thing's true: the air fryer handles it beautifully. You get that gorgeous caramelized crust, a rosy interior, and none of the smoke alarm drama that comes with traditional broiling.
What makes the air fryer version special is control. A broiler is an on-or-off situation, either the element's blazing at you or it's not. The air fryer circulates superheated air evenly, which means more consistent doneness, less guesswork, and a sear that rivals what you'd get on a screaming-hot cast iron skillet pulled from a 500°F oven.
Total game-changer for a lean cut that punishes you the second you overcook it.
Quick Recipe Summary
| Detail | Info |
|---|---|
| Prep Time | 10 minutes (+ 1–4 hours marinating) |
| Cook Time | 10–14 minutes |
| Total Time | About 20 minutes active; up to 4 hr 20 min with marinating |
| Servings | 4 |
| Difficulty | Easy |
Why You'll Love This Recipe
- Speed: From marinated fridge to dinner plate in under 20 minutes of active work.
- Tender yet lean: Flank steak has bold beefy flavor without the marbling price tag.
- Minimal dishes: One bowl for the marinade, the air fryer basket, and a sharp knife. That's it.
- Crowd-pleaser leftovers: Slice it thin and it's spectacular in sandwiches, salads, and tacos the next day.
- Kitchen-friendly: No smoking up the house, no fussing with outdoor grill coals in February.
Ingredients
For the Marinade:
- 1 flank steak (1½, 2 lb / 680, 900 g), This is the classic London broil cut. Top round (labeled "London broil" at the store) works too but is slightly leaner and less tender.
- ⅓ cup soy sauce (80 ml), Salt, umami, and acidity all in one pour. Coconut aminos works for a soy-free swap.
- 2 tablespoons olive oil, Keeps the surface from drying and helps the spices stick.
- 2 tablespoons fresh lemon juice, Brightness that cuts through the richness. Lime juice is fine in a pinch.
- 2 tablespoons Worcestershire sauce, Deepens the savory backbone. You won't taste it on its own, but the marinade would miss it.
- 2 cloves garlic, minced, Fresh is best; jarred minced garlic is acceptable but milder.
- 1 tablespoon brown sugar, A touch of sweetness to encourage browning. Honey also works.
- 1 teaspoon smoked paprika, Gives a subtle campfire vibe without liquid smoke.
- ½ teaspoon black pepper, freshly ground, Pre-ground is fine, but fresh has more punch.
- ½ teaspoon onion powder, Optional, but it rounds out the flavor.
Optional Finishing Butter (Highly Recommended):
- 2 tablespoons unsalted butter, softened
- 1 clove garlic, finely grated
- 1 tablespoon fresh parsley, minced
Mash the three together, chill into a log, and slap a round on top of the sliced steak. The butter melts into every slice. Trust me on this one.
Equipment Needed
- Air fryer (3.5-qt minimum for one steak), Basket or oven-style both work; oven-style gives you more flat surface area.
- Zip-lock bag or shallow dish, For marinating.
- Sharp chef's knife, Non-negotiable. A dull knife shreds the meat instead of slicing cleanly.
- Cutting board, One with a juice groove if you have it.
- Meat thermometer, The single most useful $15 you'll spend on kitchen gear. Pulls guesswork out of the equation.
- Tongs, For flipping without piercing the meat.
- (Optional) Wire rack that fits inside the basket, Lets air circulate underneath for a better underside crust.
Step-by-Step Instructions
1. Make the Marinade
Pour the soy sauce, olive oil, lemon juice, Worcestershire, brown sugar, garlic, smoked paprika, pepper, and onion powder into your zip-lock bag or shallow dish. Whisk or squish it around until the sugar dissolves and everything's combined. It should smell punchy, salty-sweet, and garlicky.
That's exactly right.
Why each ingredient matters: Soy sauce and Worcestershire handle salt and depth. Lemon juice tenderizes and brightens. Brown sugar feeds the Maillard reaction (the browning/crust magic) in the air fryer.
Olive oil coats the surface so nothing dries out before the crust forms. Skipping the oil or acid? The steak will taste flat and feel papery.
2. Marinate the Steak
Pat the flank steak dry with paper towels, a wet surface steams instead of sears. Lay it flat in the marinade, seal the bag, squeeze out excess air, and refrigerate.
- Minimum: 1 hour. Gets flavor into the surface.
- Ideal: 2, 4 hours. Deeper penetration, better tenderness.
- Don't go past 6 hours. The acid in the lemon and soy starts to break down the muscle fibers too much, turning the surface mushy.
Flip the bag halfway through if you remember. Not essential, but it evens things out.
3. Bring to Room Temperature
Pull the steak from the fridge 20, 30 minutes before cooking. A cold center means the outside overcooks before the inside catches up. This matters more than people think.
While it rests, preheat the air fryer to 400°F (200°C) for 3 minutes. Starting with a scorching-hot chamber is what gives you that instant sear.
4. Prep the Steak
Remove the steak from the marinade and lay it on a clean plate. Pat it thoroughly dry on both sides with paper towels. I cannot stress this enough, moisture is the enemy of browning. If the surface is wet, you'll get gray steamed beef rather than a caramelized crust.
Discard the used marinade. Do not reuse it. (If you want a sauce later, start fresh with new ingredients.)
Lightly brush or spray both sides with a thin coat of olive oil. Just a whisper. Any excess oil will pool in the basket and smoke.
5. Air Fry — First Side
Place the steak in the air fryer basket. If you can, use a small wire rack so air wraps underneath. Don't overlap or fold the steak, it must sit flat.
Cook at 400°F for 5 minutes with no peeking.
You'll hear aggressive sizzling. The air fryer's fan is spinning hot air around every square inch of that meat. After 5 minutes, a visible crust should be forming on top.
It'll look bronzed, maybe with a few darkened spots where the sugar in the marinade caramelized. That's perfect.
6. Flip and Finish
Use tongs, not a fork, to flip the steak. Piercing it releases juice you'd rather keep inside.
Cook another 5, 7 minutes, depending on thickness and your preferred doneness.
This is where the thermometer earns its keep:
| Doneness | Internal Temp (°F) | Look & Feel |
|---|---|---|
| Rare | 120–125°F | Very red center, soft to the touch |
| Medium-Rare | 130–135°F | Warm red center, slightly springy — ideal for flank |
| Medium | 140–145°F | Pink center, firmer |
| Medium-Well | 150–155°F | Slightly pink, quite firm |
My honest recommendation: Pull it at 130°F. Flank steak doesn't have intramuscular fat to keep things juicy past medium. Even medium-rare has a pleasant chew without being tough.
Over 145°F and you've essentially got a lean hockey puck.
7. Rest — The Most Important Step
Transfer the steak to a cutting board and tent loosely with foil for a full 8, 10 minutes. Do not skip this. Resting lets the muscle fibers relax and reabsorb the juices. Slice too early and all that moisture runs onto your board instead of staying in the meat.
The internal temperature will rise about 5°F during resting (carryover cooking), which is why you pull at 130°F for a finished medium-rare.
While it rests, make the finishing butter if you're using it, just roll it into a log in plastic wrap and pop it in the freezer for a few minutes to firm up.
8. Slice Against the Grain
Look at the steak. You'll see long muscle fibers running in one direction, that's the grain. Turn your knife perpendicular to those fibers and slice thin, roughly ⅛ to ¼ inch thick.
Cutting against the grain shortens those fibers, making each bite dramatically tender. With the grain? You might as well chew on a boot sole.
Look at that interior, a gorgeous pink center with a dark, lacquered crust. Pour any accumulated juices from the board over the slices.
Pro Tips For Best Results
- Score the steak. Before marinating, use a sharp knife to make shallow crosshatch cuts (about ¼ inch deep) on both sides. It lets the marinade penetrate deeper and gives more surface area for searing.
- Don't overcrowd. If your air fryer is small, cut the steak in half crosswise and cook in batches. Overlapping meat steams.
- Use the thermometer. Seriously. Every air fryer runs slightly different. Visually guessing on a thick cut isn't worth the risk of overcooking.
- Let the marinade do its job. An hour minimum. You can marinate up to 4 hours in the fridge without issues. Beyond that, the acid starts degrading the texture.
- Thin steaks cook faster. If your flank steak is under ¾ inch thick, check at 4 minutes per side. It goes from perfect to overdone fast.
- Sear before air frying? You don't need to, but if you're chasing an extra-thick crust, sear 1 minute per side in a screaming-hot skillet first, then finish in the air fryer. Adds a dish but the result is spectacular.
Variations
Italian-Style London Broil:
Swap the marinade for equal parts balsamic vinegar and olive oil, plus minced garlic, dried oregano, red pepper flakes, and a pinch of salt. Skip the soy and Worcestershire. Finish with shaved Parmesan.
Korean-Inspired:
Replace the base with soy sauce, sesame oil, rice vinegar, gochugaru (Korean chili flakes), brown sugar, and grated ginger. Top sliced steak with toasted sesame seeds and sliced scallions. Serve with kimchi.
Herb Butter Finish (Steakhouse Version):
Skip the smoked paprika. Instead, mix softened butter with fresh rosemary, thyme, garlic, and a pinch of flaky salt. The herbed butter melting over hot slices is absurdly good.
Dietary Swaps:
- Lower sodium: Reduced-sodium soy sauce, halved.
- Whole30/Paleo: Coconut aminos instead of soy sauce, omit brown sugar.
- Dairy-free: Skip the finishing butter or use quality olive oil and herbs instead.
What To Serve With It
- Starches: Garlic mashed potatoes, roasted baby potatoes, or a creamy polenta. Something soft to carry those juices.
- Greens: A simple arugula salad with lemon vinaigrette, or roasted broccolini with chili and garlic.
- Veggies: Air-fry some asparagus or green beans in the basket right after the steak, same temp, 5 minutes, done.
- Bread: Crusty sourdough for mopping up any juices left on the plate.
- Drink: A medium-bodied red, Malbec, Cabernet Franc, or a Côtes du Rhône. Nothing too heavy; flank steak is a lean, straightforward cut that pairs well with wines that have some acidity rather than massive tannins.
Storage & Reheating
Refrigerator: Store sliced steak in an airtight container with any collected juices. It keeps well for 3, 4 days. The juices act as a natural sauce and keep things moist.
Freezer: Layer slices between parchment paper in a freezer bag. Press out excess air. Keeps for up to 2 months.
Thaw overnight in the fridge.
Reheating:
- Best method: Let slices come to room temperature (15 min), then sear briefly in a hot skillet, 30, 60 seconds per side. This restores the crust without overcooking.
- Microwave shortcut: Place slices in a microwave-safe dish with a splash of broth. Cover loosely. Heat in 30-second bursts.
- Cold option: Skip reheating entirely. Leftover London broil is phenomenal cold in sandwiches, grain bowls, or wraps.
Frequently Asked Questions
Can I use top round instead of flank steak?
Yes. It's slightly leaner and a bit firmer, but the same techniques apply. Don't cook it past medium or it'll be tough.
Do I have to marinate it?
No, but you absolutely should. Flank steak is lean and somewhat tough without the tenderizing benefit of a good acidic marinade. Even 30 minutes makes a difference.
What if I don't have a meat thermometer?
Use the touch test: press the steak with your finger. Rare feels like the fleshy part of your palm below the thumb when your hand is relaxed. Medium-rare feels like that same spot when you lightly touch your thumb to your index finger.
Medium, thumb to middle finger. It's imprecise, but it works in a pinch.
My air fryer smokes a lot. Why?
Excess oil or marinade dripping into the bottom of the basket. Pat the steak completely dry, use less oil, and line the drip tray with a piece of bread to absorb grease.
Can I cook it from frozen?
Technically yes, but the timing becomes unpredictable and you'll never get a good crust on cold, wet meat. Thaw overnight in the fridge for best results.
How do I know which way the grain runs?
Look for parallel lines running the length of the steak. Those are the muscle fibers. Cut across them, not with them.
If the fibers look confusing, poke the raw steak with a knife, make a small test slice, and check the direction before committing.
Final Thoughts
If you've been overcomplicating London broil, or worse, drying it out under a too-close broiler, the air fryer is going to reset your expectations. The circulating heat wraps around the meat evenly, the marinade caramelizes into a gorgeous crust, and the whole process takes barely twenty minutes of active time.
Grab a flank steak this week. Whisk together that ten-minute marinade. Let the air fryer do what it does best.
Slice it thin, pile it on a board with a slab of herb butter melting over the top, and tell me this isn't one of the easiest, most satisfying dinners you'll make.
It just is.