Preheat oven to 400 F, and line or grease a baking sheet.
Cut tomatoes in half and use the bottom half of tomatoes.
Using a knife slice around the inner edges of tomato halves and with a spoon, scoop out the center of tomatoes. Be sure to dump out all seeds, pulp and juices. Turn tomato halves over on a plate to drain.
In a medium bowl combine all the remaining ingredients except for the cheese slices. Mix together and break up tuna into flakes. Mix until combined.
Turn the tomato halves over and fill each hollowed out tomato with tuna salad mixture.
Cut the 2 cheese slices in half and top each tomato with cheese.
Bake for 15 minutes. Remove from oven, cool and serve.