Prepare Citrus Marinade: Blend all ingredients in small bowl.

Combine marinade with tuna in large resealable plastic food storage bag. Seal bag; turn to coat. Marinate in refrigerator 1 hour for each inch of thickness, turning occasionally. Drain tuna; discard marinade.

To prevent sticking, spray grill with nonstick cooking spray. Prepare coals for grilling. Place tuna on grill, 4 inches from hot coals. Grill 8 to 10 minutes or until tuna flakes easily when tested with fork, turning once. Or, place tuna on rack of broiler pan coated with nonstick cooking spray. Broil 4 inches from heat, 8 to 10 minutes or until tuna flakes easily when tested with fork. Slice tuna into 1/4-inch-thick slices; set aside.

Place 2 cups water in large saucepan; bring to a boil over high heat. Add beans; cook 2 minutes. Drain; rinse with cold water and drain again.

Place lettuce on large serving platter. Arrange tuna, beans, potatoes, tomato, egg whites and onion on lettuce. Sprinkle servings with olives. Serve with low calorie salad dressing, if desired.

This recipe yields 4 servings.

Exchanges Per Serving: 2 Starch, 3 Meat, 2 1/2 Vegetable.

Nutrition Facts: Calories 373; Calories from Fat 16%; Total Fat 7g; Saturated Fat 1g; Protein 35g; Carbohydrates 45g; Cholesterol 48mg; Sodium 160mg; Dietary Fiber 6g.