Essentially a lasagna with tortillas standing in for noodles, this is one of those dishes that can miraculously be on the table in short order, made from things you most likely have in your pantry and fridge. If you don't like, or you don't have, one of the ingredients, skip it. Or, if you have something else that you think might be appealing all layered in (like slivered bell peppers to sauté with the onions, kale, chopped, cooked broccoli — whatever the people in your home will eat), then fling it on in.