1 ounce dried chile arbols, seeded

1/2 cup boiling water

3 cups chopped onion

1 cup water

1/2 cup chopped tomatillos (about 2)

2 teaspoons dried oregano

1-1/2 teaspoons ground cumin

1/2 teaspoon salt

3 garlic cloves

1 (8-ounce) can tomato sauce

Combine chiles and boiling water; let stand 30 minutes. Drain.  Combine chiles, onion, and next 6 ingredients (onion through garlic) in a medium saucepan. Place over medium-high heat; bring to a boil. Reduce heat; simmer 20 minutes. Remove from heat; cool 15 minutes. Place onion mixture in a blender or food processor; process until blended (do not overblend). Add tomato sauce; stir well.