Fruity Tuna-Salad Pita Sandwiches

Slice 1 hard-cooked egg in half lengthwise, and remove yolk; reserve egg yolk for another use. Dice egg white halves; set aside. Prepare grill or broiler. Sprinkle 1 tsp lemon juice and a dash of black pepper over tuna. Place the tuna on a grill or broiler rack coated with cooking spray; cook 4 min on each side until tuna is medium-rare or desired degree of doneness. Coarsely chop tuna. Combine tuna, diced egg white, 1/4 cup diced celery, 1/4 cup raisins, 2 tbsp minced green onions, 3 tbsp reduced-fat mayonnaise, 1 tsp Dijon mustard, 1 (8-ounce) can unsweetened pineapple tidbits, drained in a bowl. Line 2 (5-inch) whole-wheat pitas, cut in half with 1/3 cup lettuce and 2 tomato slices. Divide the tuna mixture evenly among pita halves