Prepare these tomatoes to serve as a side dish with oven-cooked meals. They can be stuffed up to 4 hours in advance, refrigerated, then heated (allow a longer heating time in this case).
Core tomatoes and cut a thin slice from the top of each. Scoop pulp and juice into a skillet and mash pulp. Place tomato shells cut side down on a paper towel to drain.
Add celery, onion, green pepper and curry powder to tomato pulp and juice. Cook, stirring, over medium heat for about 5 minutes or until vegetables are tender. Add lentils and cook, stirring, until mixture is thickened.
Spoon lentil mixture into tomato shells. Sprinkle with Parmesan. Place stuffed tomatoes in 4 muffin cups. Set muffin pan on a baking sheet.
Bake in preheated oven for 10 minutes or until heated through.