Grilled Yellowfin Tuna with Romaine and Tropical Fruit

Combine first 7 ingredients in a large bowl; add 1 teaspoon oil, 1/4 teaspoon salt, and 1/8 teaspoon pepper, tossing to combine.

Heat a large heavy grill pan over medium-high heat. Rub remaining 2 teaspoons olive oil over tuna; sprinkle tuna evenly with remaining 1/4 teaspoon salt and 1/4 teaspoon pepper. Coat pan with cooking spray. Add tuna to pan; cook 3 minutes on each side or until desired degree of doneness. Arrange 1 1/2 cups salad on each of 4 plates; top each serving with 2 tuna steaks. Serve with lime wedges, if desired.