Beef tripe simmered for hours in a rich red chile broth with hominy. This high protein, traditional family weekend soup is famous as Mexico's beloved hangover remedy.
Thoroughly rinse the beef tripe and beef feet under cold running water; cut the tripe into bite-sized pieces for even cooking.
In a large stockpot, combine the tripe, beef feet, half the onion (quartered), bay leaves, and garlic. Cover with 14 cups of water and bring to a rolling boil over high heat.
Reduce heat to a bare simmer, skimming any foam or impurities that rise to the surface. Simmer gently, uncovered, for 2 hours to develop deep broth flavor.
Meanwhile, toast the guajillo and ancho chiles in a dry skillet over medium heat for about 2 minutes until fragrant, taking care not to burn them. Remove seeds and stems, then soak the chiles in hot water for 20 minutes until completely softened.
Blend the soaked chiles with 1 cup soaking liquid and the remaining half onion until completely smooth, then strain through a fine-mesh sieve into the pot.
Add oregano, crushed red pepper flakes, black pepper, and salt to the pot. Stir well, and continue simmering for 1 more hour.
Add hominy to the soup and simmer for a final 30-40 minutes, until the tripe is tender but not mushy. Adjust salt and pepper to taste.
Remove bay leaves and discard any bones from the beef feet. Serve hot, garnished as desired.