In a medium skillet, heat the butter or oil to medium heat. Add the onions and serrano. Season lightly with salt and pepper and saute for 5 minutes.

In a bowl, whisk the eggs with the milk or water. Season lightly with salt and pepper. To the onions add the tomatoes and saute for 1 minute. Add the eggs and turn heat down slightly. Let the eggs set for a few seconds before gently folding in towards the center.

Once eggs are pretty much cooked, I like to cover with lid and let them sit for 1 minute. To the plate add two tostadas, salsa, eggs, queso fresco, more salsa, cilantro, green onions and more minced serrano if you like. Yields 2 servings.