Saute the onion and garlic in oil in a saucepan until the onions soften.
Add the remaining ingredients.
Bring to a boil, then reduce heat and simmer about 25 minutes or until tomatoes are soft.
Puree with a stick blender, or allow to cool down and puree in a food processor or blender.
How to make enchiladas as shown:
Take the meat off a rotisserie chicken and shred with your fingers.
Toss with about a cup of the enchilada sauce.
Heat about half inch oil in a skillet and briefly fry the corn tortillas a few seconds to soften.
Fill with meat mix, roll up, and place seam side down in a baking pan that has a layer of sauce in the bottom.
Top with shredded cheese (cheddar or Oaxaca Mexican melting cheese) and bake at 375F for about 10-15 minutes to melt the cheese.
This uses about half the sauce (one quart) on a pan of 6-8. You can feel free to make another pan or freeze the rest in a ziploc.
You can freeze extra chicken, or I used the extra meat rolled into flour tortillas and fried as flautas, which I served with freezer guacamole, sour cream, and salsa.