Preheat oven to 350°. Lightly oil baking dish. Prepare vegetable “containers” – slice bell peppers in horizontal rings about ¾-inch thick, removing center seeds and white ribs; for avocados, cut in half across the middle, remove the pit, and cut ¾-inch slices. Remove peel. For tomatoes, slice the top off and carefully scoop out the insides. If necessary, slice a sliver off the bottom to level it. Place vegetables in baking dish and lightly season. Gently break an egg inside opening. Bake 20-25 minutes until egg whites are set. Shallow vegetables, such as pepper rings, will take less time, while tomatoes make take longer to cook egg white. Remove from oven and add toppings. Serve immediately.