Cut each tomato in half crosswise, and set aside.
Cut each bread slice with a 3 1/2-inch cookie cutter. Toast bread rounds on each side, and set aside.
Cook bacon in a large skillet until crisp; drain well, reserving 2 tablespoons bacon drippings in skillet. Crumble bacon, and set aside.
Sauté green pepper and onion in reserved drippings until tender. Stir in salt.
Place toast rounds on a baking sheet. Top each toast round with a tomato half, sautéed mixture, cheese, and crumbled bacon. Broil until cheese melts.