Preheat the oven to 375 degrees F.
Line a deep 8-inch by 10-inch baking pan with aluminum foil. Spray lightly with nonstick spray, making sure to coat the sides as well as the bottom.
In a large bowl, combine egg substitute, milk, cumin, and taco seasoning. Whisk the mixture for 1 minute, until mixed thoroughly.
Add onion, garlic, and bell pepper, and stir well. Carefully transfer the egg mixture to the baking pan.
To the pan, evenly add black beans, corn, and green chiles. Sprinkle with cheese.
Bake in the oven for 1 hour, until the top has puffed and the center is firm. Allow it to cool slightly before cutting.
Cut into four slices. If you like, finish it off with the optional toppings!
PER SERVING (1/4th of recipe, 1 large piece): 188 calories, 3g fat, 590mg sodium, 17g carbs, 2.5g fiber, 5g sugars, 22g protein