Preheat broiler. For raita, in a small bowl combine yogurt, cucumber, onion, snipped mint, and sugar. Season to taste with salt and pepper; set aside
Trim fat from meat. Sprinkle meat with lemon-pepper seasoning. Place meat on the unheated rack of a broiler pan. Broil 3 to 4 inches from heat, turning meat over after half of the broiling time. Allow 15 to 17 minutes for medium-rare (145 degree F) and 20 to 22 minutes for medium (160 degree F).
Cut steak across the grain into thin slices. If desired, garnish steak slices with mint leaves. Serve with raita. Makes 4 servings.