Seed the ancho chiles and boil them in water. Add them to a heavy-duty blender to blend.
Remove the lamb from the fridge and let sit out for 15 to 20 minutes. Score the fat with a sharp knife, creating a crisscross pattern. Rub thoroughly with salt and pepper, then some of the ancho liquid and chipotle chiles. Place celery, garlic, tomatoes, carrots, thyme, oregano, bay leaves and 1 onion in a roasting pan along with the beer, stock and chile powder. Put a roasting rack on top of the vegetables and liquid and place the lamb in the roasting pan.
Roast until the lamb starts to turn deep brown, approximately 4 hours. Cover tightly with foil and continue to roast until an instant-read thermometer inserted in the thickest part (do not touch bone) registers 180 degrees F. Let stand for 20 to 30 minutes to cool. Once cool enough to handle, remove the roast from the roasting pan and begin to shred all of the meat off to a bowl with forks and your fingers.
Strain the liquid from the roasting pan into a blender and blend thoroughly until smooth (this is what I call lamb butter). Pour over the lamb and mix together, adding some water if it becomes too thick.
Chop your cilantro and remaining onion and mix together in a small bowl.
Serve the lamb on corn tortillas with homemade Salsa. Top with cilantro-onion mixture, Cotija and radish. Enjoy.
Chile De Arbol Tomatillo Salsa:
Heat a grill for cooking at medium heat. Grill or roast the garlic, tomatillos, tomatoes and onions, turning occasionally, until charred. Let cool.
Bring 3 cups water to a boil in a medium pot over medium heat, then add garlic, tomatillos, tomatoes, onions, chiles de arbol, anchos, guajillos, cilantro and sugar and boil together for 8 to 10 minutes. Let cool, and then drop into a blender and blend until pureed, but a little bit chunky. Season to taste.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.