8 lb lamb stew meat or beef chuck roll; have butcher clean and cube meat
FOR THE SAUCE:
Place lightly toasted dried chiles in a small sauce pot and cover with water. Cook on low heat for about 20 minutes until chiles are soft. Remove from water. Do not discard remaining water.
In two batches, place all ingredients except for the beer and lamb into a blender and puree until smooth. Adjust thickness of sauce with remaining chile cooking water. Place two batches of sauce in a large container and whisk together to combine. Pour in beer and stir to combine with sauce.
FOR THE BORREGO:
Preheat oven to 225 degrees.
Place lamb in a Dutch oven or oven-safe container and pour sauce over meat, making sure each piece of lamb is thoroughly coated.
Cover tightly with foil and then Dutch oven lid. Cook for 6-7 hours; meat should be fork tender and easily fall apart. Remove from oven and let rest for one hour. Serve with your favorite sides.