1. Preheat oven to 400°.
2. Place chiles on a baking sheet; bake at 400° for 4 minutes or until dark. Cool; remove stems and seeds.
3. Sprinkle pork with salt and pepper. Heat oil in a large Dutch oven over medium-high heat. Add pork to pan; cook 5 minutes or until browned. Remove pork from pan. Wipe drippings from pan; return pork to pan. Add broth and next 5 ingredients (through onion), scraping pan to loosen browned bits. Add guajillo chiles and 1 tablespoon adobo sauce; reserve remaining chipotle chiles and sauce for another use. Bring to a boil; cover, reduce heat, and simmer 2 hours or until pork is tender.
4. Remove chiles, onion, garlic, and 1 cup cooking liquid; place in a blender. Remove center piece of blender lid (to allow steam to escape); secure blender lid on blender. Place a clean towel over opening in blender lid (to avoid splatters). Blend until smooth; return to pan. Stir in hominy; cook 10 minutes.