Succulent London Broil

London broil isn’t actually British, despite the name. It’s an American technique born from the need to tenderize tough but flavorful flank steak, and this recipe nails the formula: acidic marinade, hot broil, thin slice against the grain. Done correctly, the result rivals far more expensive cuts.

Scoring the steak on both sides isn’t decorative. The shallow crosshatch cuts let the marinade penetrate deeper into the meat and shorten the broiling time. Without scoring, the marinade only flavors the surface; with it, the marinade works into the muscle fibers.

The full three-hour marinade is the minimum. Flank steak needs time for the vinegar to break down the tough connective tissue. Overnight is even better; the meat ends up significantly more tender. Don’t shortcut this; the marinade is doing structural work, not just flavoring.

High heat and short cook time are essential. Four minutes per side at 3 inches from the broiler element delivers a properly seared crust and a pink center. Cook longer and flank steak goes from tender to chewy in under a minute.

The slice-against-the-grain rule is the most important step. Flank steak has highly visible muscle fibers running in one direction. Cut perpendicular to those fibers, on a sharp diagonal angle, into thin slices. Cut with the grain and you get jaw-tiring strips of beef jerky.

Pro Tips

• Let the steak come to room temperature for 30 minutes before broiling for even cooking.
• Use an instant-read thermometer; pull at 130°F (54°C) for medium-rare, the only acceptable doneness for flank steak.
• Rest the steak 10 minutes before slicing; cutting hot meat loses all the juices.
• A sharp slicing knife with a thin blade gives the cleanest slices.

Variations

• Add a tablespoon of soy sauce to the marinade for deeper umami.
• Substitute red wine vinegar with balsamic for a sweeter glaze.
• Serve over a salad of arugula, tomato, and red onion for steak salad.