Roast 2 pounds of tomatoes over medium heat until soft and partially charred in a large skillet. Repeat this process with 10 tomatillos, 4 garlic cloves, and 2 large halved onions.
Add charred ingredients and ¼ cup cobanero chile flakes to a blender and puree until smooth. (Makes about 1 quart).
In a large pot, heat a little vegetable oil. Add sauce and cook over high heat, stirring until thickened (about 5 minutes). Season with salt.
Add meat, vegetables, or other stew ingredients of your choice. Simmer until fully cooked.