4 pounds lamb shoulder – bone-in, cut into 3–4 large pieces
2 pieces banana leaves – rinsed and passed over flame to soften
1 pieces white onion – thickly sliced
2 pieces bay leaves
4 pieces avocado leaves – lightly toasted
15 ounces chickpeas (canned) – drained and rinsed
2 cups water – for braising
1 teaspoons kosher salt – for broth
corn tortillas – warmed (for serving)
white onion – finely chopped (for serving)
cilantro – chopped (for serving)
limes – cut into wedges (for serving)
salsa – (for serving)
Instructions
Stem and seed the dried guajillo chiles and dried ancho chiles, then toast them in a dry skillet over medium heat until fragrant and pliable, 30–45 seconds per side.
Place the toasted chiles in a bowl and pour the hot water (for soaking chiles) over them. Soak until softened, about 15 minutes.
In the same dry skillet, toast the cumin seeds, black peppercorns, and whole cloves until fragrant, about 1 minute, then remove from the heat.
Drain the chiles, reserving their soaking liquid. Blend the softened chiles with the garlic, the roughly chopped white onion, white vinegar, Mexican oregano, the toasted spices, and the kosher salt (for adobo), adding enough of the reserved soaking liquid to form a smooth, thick adobo.
Place the lamb shoulder pieces in a large, heavy lidded pot or Dutch oven and coat thoroughly with the adobo. Cover and refrigerate to marinate for 1–2 hours.
Heat the oven to 325°F (165°C). Line the pot with the banana leaves (soften them first by passing over a low flame until pliable), leaving overhang to fold over the meat. Scatter the thickly sliced white onion, bay leaves, and the chickpeas (canned) in an even layer. Set the adobo-coated lamb on top and pour in any remaining adobo. Tuck in the avocado leaves (toast them briefly in the skillet until aromatic just before adding). Pour in the water (for braising) around the sides.
Fold the overhanging leaves over the meat to enclose, then cover the pot tightly with its lid or heavy foil. Bake until the lamb is very tender and shreds easily, 3.5–4.5 hours (a fork should slide in with no resistance).