In another skillet melt a little bit of butter, and lightly fry the tortillas one at a time on both sides.
Melt a tablespoon of the butter in a large skillet. Add chopped onions and saute until onion is translucent. Add the tomatoes, you can break them up with a wooden spoon or chop them up like I did. Chop the chipotle pepper and add to the skillet and season with salt and pepper if needed. Simmer sauce for about 20 to 30 minutes.