Jalisco Style Birria

Name: Jalisco Style Birria
Prep time: 30 min
Cook time: 8 h
Total time: 8 h 30 min
Cuisine: Mexican
Ingredients: 4 pounds shoulder or neck roast; 12 guajillo or ancho chiles, (about 4 ounces); 2 pounds Roma tomatoes, sliced in half; 1 white onion, sliced in half; 1 head garlic, separated but not peeled; 2 tablespoons black peppercorns; 4 to 6 whole cloves; 2 teaspoons cumin seeds; 1 tablespoon salt; 3 bay leaves; 1 tablespoon dried Mexican oregano; 1 cup Mexican beer ((I use Negro Modelo or Bohemia)); 1/4 cup pineapple or cider vinegar; Banana leaves; 1 cup corn masa or flour ((to seal the pot)); Cilantro and chopped white onion, for garnish; corn tortillas