To make the marinade
Heat a large, dry skillet over medium heat. Add the dried chile peppers and toast them for no more than 20 seconds per side, taking care not to burn them.
Transfer them to a medium saucepan and add the water, place over medium heat and cook for 12 to 15 minutes, until the peppers have softened and rehydrated.
Transfer the peppers to a blender. Add 2 cups of their cooking liguid (discard the remaining liquid), the vinegar, tomato, onion, garlic, oregano, cinnamon, allspice, black pepper, cloves (stems removed) and salt; puree until smooth.
Wipe out the medium saucepan and add the oil. Place over medium heat for 1 to 2 minutes, then add the pureed marinade, being careful to avoid any splatters. Partially cover, and cook for 10 to 12 minutes, stirring once or twice, until the color darkens and the mixture thickens to a pastelike consistency.
Rinse the lamb and pat dry with paper towels. Place in in a large, nonreactive dish. Use the marinade to cover it completely, rubbing the mixture into the meat. Cover and refrigerate for 2 to 24 hours.
To make the vegetable base
Just before the lamb is finished marinating, prepare the vegetable base. Have a large roasting pan at hand with a rack that fits inside, preferable with some space underneath. Remove the lamb from the refrigerator about 20 minutes before you place it in the over.
Combine the onions, carrots, potatoes, and soaked and drained garbanzo beans in a large raosting pan. Pour the beer and water over the top. Add the bay leaves and season with salt to taste; toss to combine. Place the roasting rack over the mixture.
To make the meat
Preheat the over to 325 degrees.
Unfold the banana leaves and arrange a few layers of them on the roasting rack, leaving a generous amound of overlap on the pan long sides for wrapping the meat (alternatively, you may use a few long pieces of aluminum foil). Place the meat on top of the leaves and use all of the marinade to cover it. PLace the avocado leaves, if using, on top of the meat, then fold the leaves over to cover the meat. If using the foil, poke a few small holes near the bottom edges to allow the meats juices to fall into the vegetable base below during cooking. The juices will natually fall through the spaces between the banana leaves.
Cover the banana leaf package or foil package tightly with a layer of foil. Slow-roast for 8 to 10 hours; until the meat comes off the bone easily and the vegetables should be well seasoned and tender. Transfer to the stovetop (off of the heat), and let everything rest for 15 to 20 minutes before opening the package. Discard the avocado leaves, if using.
Serve with lime wedges, warmed corn tortilla and a salsa you like.
Credit Pati Jinich