Start by cleaning the Beef Tripe (Honeycomb And Book): rinse well under cold water, trim any excess fat, then rub with a little White Vinegar and Coarse Salt. Rinse again until the water runs clear.
Place the cleaned Beef Tripe (Honeycomb And Book) and Beef Foot in a large stockpot and cover with cold Water. Add halved White Onion, a couple of Bay Leaves, several Black Peppercorns and a generous pinch of Kosher Salt. Bring to a boil, skim any foam, reduce heat and simmer gently for 2–3 hours, or until the tripe is tender and the broth is flavorful.
While the meat simmers, prepare the chile base: remove stems and seeds from the Dried Guajillo Chiles and Dried Ancho Chiles. Toast them briefly in a dry skillet until fragrant (30–60 seconds), then soak in hot Water for 15–20 minutes to soften.
In a blender, combine the rehydrated chiles (with a little of their soaking liquid), toasted garlic cloves and a pinch of Ground Cumin. Add a small spoonful of the reserved caldo from the pot to loosen, and blend to a smooth sauce. Taste and season lightly with Salt and a pinch of Dried Mexican Oregano or Mexican Oregano as you blend.
Strain the chile sauce through a fine-mesh sieve into a bowl to remove skins and seeds, pressing to extract as much flavor as possible. Return the strained sauce to the pot with the simmering tripe and beef foot, stirring to combine.
Continue to simmer the menudo for another 30–60 minutes so the tripe soaks up the chile flavor and the broth thickens slightly. Adjust seasoning with more Kosher Salt or Salt and freshly ground pepper to taste.
Finish the soup by stirring in a small pinch of Crushed Chile De Árbol if you want extra heat. Remove the Beef Foot if it has released its collagen and shred any meat, then return it to the pot.
Serve the menudo hot, garnished with chopped White Onion and fresh Cilantro, and wedges of Lime to squeeze over each bowl. Offer warm Corn Tortillas alongside for dipping or making small tacos.
