2. In a small skillet, heat the oil over medium heat and cook peppers and mushrooms until softened, about 5 minutes.
3. Blend eggs, milk and flour in a blender until smooth. Add cooked vegetables and tomatoes to the egg mixture, stir well and then pour egg mixture into the baking pan.
4. Bake for 20 minutes. Remove from the oven when the eggs are cooked through.
5. To serve, top with the cheese and salsa. Then, roll up the omelet, starting at the narrow end of the pan. Cut into 6 slices and place on a platter.