Cut tops off of tomatoes about 3/4" down from top. Save for "lids". Using a spoon or melon baller, scoop out insides of tomatoes, leaving outer layer intact. Discard insides, or you can discard seeds, and save pulp for use in filling if desired.
2Sprinkle inside of tomatoes with salt, and invert onto rack to drain. This will make the tomatoes firmer for baking. Let sit inverted while you prepare filling, at least 20 minutes.
3To prepare filling:
Over high heat brown beef and onions in olive oil and cook until golden brown, 8-10 minutes.
Add bell pepper and garlic and stir in. Let cook 2 minutes.
4Add remaining ingredients and bring to a boil. Stir then reduce heat to simmer, and cover. Let cook for 10-15 minutes until liquid is just absorbed. Rice will still be a little chewy.
5Stuff hollowed out tomatoes with about 1/2 cup of filling each, mounding slightly on top. Place in large baking dish, the tomatoes should just touch each other in the pan. Place tomato top "lids" back on tomatoes. Cover with foil and place in preheated oven.
Bake for 30-40 minutes until hot throughout. Tomatoes should still hold their shape.