The marinade for this London Broil is really delicious. It's one of my favorite dishes to serve company or for birthday dinners and other special occasions because it's so delicious, despite how easy it is to prepare. It makes a great focal point for a complete meal that includes a steamed fresh vegetable (or a tossed fresh green salad), garlic mashed potatoes, and an Italian baguette or fresh baked rolls.
Combine shallots, soy sauce, lemon juice, balsamic vinegar, olive oil, thyme, oregano, and garlic in a large zip-lock plastic bag. Pierce steak with a fork in several spots on both sides. Add steak to bag; seal. Marinate in refrigerator for at least 2 hours (or up to 8 hours), turning every 30 minutes to ensure even marinating.
Preheat broiler. Spray broiler pan with non-stick cooking spray; set aside.
Remove steak from bag; discard marinade. Scrape shallots and garlic from steak; discard shallots and garlic.
Place steak on prepared broiler pan. Sprinkle steak evenly with salt and pepper.
Broil steak 4 inches from heat for 6 minutes on each side or until desired degree of doneness. Let stand 10 minutes before slicing against the grain.