Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   6      ounces        dried ancho -- pasilla or Anaheim chiles
   3      cups          hot water
     1/4  cup           tomato sauce or tomato puree
   1      clove         garlic -- minced
     1/4  cup           salad oil
   1 1/2  teaspoons     salt
   1      teaspoon      oregano -- crumbled
     1/4  teaspoon      cumin

Preparation:

Place chiles on a baking sheet. Toast lightly in a 400-degree oven for 3 or 4 minutes only, or until they give off a mild aroma. If you burn the chiles, they will be bitter. Remove from oven and let cool to tough. Remove and discard stems, seeds, and any pink pithy material inside the chiles. Rinse in cool water, drain and then cover with hot water; let stand 1 hour. Place chiles in a blender with enough of the water to blend. Mix until smooth. Alternately, scrape the pulp from the skin with a table knife, then put through a strainer.) Add remaining water, tomato sauce or tomato paste, garlic, salad oil, salt, oregano, and cumin. Simmer sauce gently for 10 minutes, stirring occasionally. Makes 3-1/2 cups. Source: Sunset Mexican Cookbook