Clean crabs by removing gills and cutting off the eyes and mouth.
Place crabs on pan or aluminum foil. Place on grill over a low fire. Baste the crabs with the Lemon Butter Sauce. Cook for 5 to 6 minutes on each side. Continue to baste during cooking. Before serving, top each crab with a slice of tomato and a small amount of mozzarella cheese. Allow cheese to melt. Remove from grill. Serve immediately.
Add lemon juice and other seasonings. Seasonings may be adjusted for personal taste. Allow to simmer for about 20 minutes.