In a medium bowl, mix the crab meat, yogurt (or mayonnaise), celery, onion, tomato, bell pepper, parsley, and vinegar. Season with salt, pepper, and stevia. 2 Slice off the tops of the tomatoes and set aside. Carve out the inside of the tomatoes, leaving the outside intact. 3 Stuff the crab mixture into the tomato cups if desired. Enjoy immediately, or place in a covered and store in fridge for a quick and healthy lunch!