Cut bread crosswise into two, about 7 inches long. Cut each horizontally, press pieces with a large stockpot ( I use a small cutting board) weighted with heavy cans or books. Press with your own weight until bread flattens to 1 inch thickness. Leave weights in place.
Heat 1 teaspoon olive oil over medium high heat in large skillet. Saute onions and peppers until they become somewhat blackened, about 20 minutes. Remove from heat.
While veggies are cooking, combine garlic, chopped chipotles, and vegan mayo in small bowl. Stir well.
Spread mayo mix on all four halves (use more or less to your liking, it is spicy). Lay onions and peppers, topped by tomato slices, over two halves. Top the tomatoes with salt and pepper. Place other two halves on top to form two sandwiches.
Heat 1 tablespoon olive oil in a large skillet or griddle over medium heat. Place sandwiches in skillet, weigh them down with a large plate or another skillet. Cook for 4 minutes each side, checking to make sure they do not burn. Serve right away.