Guadalajara "drowned" sandwiches (Tortas ahogadas)

1. Cover the pork shoulder with water, add the garlic, bay leaves and salt and simmer gently for 2 hours until tender; lift it out and shred.

2. Boil the tomatoes in water for 5 minutes, then blend with the garlic, oregano, salt and a mug of the pork broth, strain and simmer for 10 minutes – this is the thin, warm tomato sauce the sandwich is "drowned" in.

3. For the hot sauce, toast the árbol chilies in a dry pan for a few seconds, then blend with the cider vinegar, garlic, salt and a little water until smooth.

4. Slice the red onion hair-thin and mix with the juice of a lime and a pinch of salt. Mash the cooked beans with a fork.

5. Split the rolls lengthwise (ideally crusty, thick-skinned birote salado), spread the bottom halves with bean purée and fill generously with the shredded meat.

6. Put the sandwiches in deep plates, drench them in the tomato sauce and, to taste, in the hot sauce too; serve at once with pickled red onion and lime.

Tip: Taste the hot sauce first – árbol chilies are very hot; locals ask for a "media ahogada", half-drowned, when they want to go easy.