Combine all marinade ingredients, except steak, in a large resealable plastic bag. Remove half of marinade mixture to a small bowl (this half will be used as the salad dressing). Add steak to plastic bag with marinade, toss to coat and seal. Marinate in refrigerator at least 10 minutes, up to 12 hours. Remove steak from bag and discard marinade.
Heat a large nonstick skillet coated with cooking spray over medium-high heat. Add onion; sauté 3 minutes. Add tomatoes, cucumber and carrot; sauté 2 minutes. Place sautéed vegetables and lettuce in a large bowl; toss gently to combine.
Preheat your outdoor gas grill, grill pan or broiler. Coat your cooking surface with cooking spray.
Cook steak 5 minutes on each side or until desired degree of doneness. Remove to a cutting board, tent loosely with foil, and let stand 5 minutes. Meanwhile, divide salad equally between 4 plates. Thinly slice steak across the grain, lay slices on top of salad, and drizzle with remaining marinade.
Garnish with green onions, fresh mint, Thai basil, and/or roasted peanuts, if desired.