INGREDIENTS 1/4 cup  lemon juice 3 Tbsp  extra-virgin olive oil 2 tsp  Dijon mustard 1/4 tsp  salt, or to taste Freshly ground pepper, to taste 1 pound  top round steak, 1 1/2 inches thick, trimmed 4 cups  romaine lettuce, chopped 1  medium cucumber, diced 1  large tomato…