4 firm, ripe tomatoes
2 tsp. lemon juice
1 tbsp. butter
1 sm. yellow onion, chopped
1/2 stalk of celery, chopped
1 med. carrot, peeled, grated
1 tbsp. flour
1 c. milk (skim or regular)
1 can (6 1/2 oz.) water-packed tuna, drained, & flaked
1/4 tsp. black pepper
3 tbsp. fine, dry bread crumbs
1/2 c. shredded Monterey Jack cheese
1 tsp. Parmesan, grated

Preheat oven to 350 degrees. Core and hollow out tomatoes. Sprinkle insides with lemon juice. Drain upside down on paper towels for 10 minutes. In saucepan, melt butter, add onion, celery, and carrot and cook until soft, about 5 minutes. Blend in flour and cook, stirring, for 1 minute. Add milk and cook, stirring constantly, until thick - about 3 minutes.

In a bowl, stir tuna, pepper, 2 tablespoons bread crumbs, the sauce, and all but 1 tablespoon of the cheese: Monterey Jack. Spoon the mixture into the tomatoes and set them in a baking pan just large enough to hold them. Sprinkle tops with remaining bread crumbs and cheese. Bake uncovered for 15 minutes.