Preheat oven to 450°F (232°C) or set broiler to high
Pat the London broil dry and season generously with salt and black pepper
Optional marinade: combine olive oil, minced garlic, soy sauce or Worcestershire, and a splash of vinegar or lemon juice; marinate 4–24 hours
Place oven-safe skillet or broiler pan on the stove or in the oven as needed
Sear: heat a skillet over high heat, add a thin layer of oil, and sear the steak 2–4 minutes per side
Transfer to oven (if oven method): roast 6–12 minutes to reach desired doneness
Transfer under broiler (if broiler method): broil 4–8 minutes per side depending on thickness
Check internal temperature:
Rare: 125°F (52°C)
Medium-rare: 130–135°F (54–57°C)
Medium: 140–145°F (60–63°C)
Medium-well: 150–155°F (66–68°C)
Remove steak and rest 10–15 minutes
Slice thinly against the grain
Optional finishing: brush with reserved marinade or herb butter, then serve