heat olive oil in a saucepan. Add onion and salt and saute over med. heat for about 5 min. Add cumin and chili powder. and saute 5 more min.

Add chopped tomatoes and water. Bring to a boil, cover and simmer 30+ min. Add the cayenne and black peppers, garlic when you would like. Add the cilantro after the sauce is finished. You can leave the sauce chunky or puree part or all of it in the blender.