Step 1 - In a bowl, mix the onion, garlic, oregano, cloves, salt, vinegar and oil and rub the meat with the mixture. Place the meat with the marinade in a bowl, cover with plastic wrap and marinate refrigerated for at least 12 hours.
Step 2 - Preheat the oven to a very high temperature (230°C).
Step 3 - In a baking dish, place the onions and carrots. On top put the meat, reserving the marinade. Roast the meat for 15 minutes until lightly browned.
Step 4 - Reduce oven temperature to low (125°C). In a bowl, mix the reserved marinade with the beer or wine and drizzle the meat with the liquid. Continue cooking the meat for 3½ hours, basting constantly with cold water (total 3 cups).
Step 5 - Step 5 - Remove the meat and vegetables from the baking dish, cut the meat into thick slices and place in a pot along with the vegetables and cooking juices, add more water to cover the ingredients. Cook over low heat for 2 to 3 hours, adding more water if necessary. Remove excess fat and serve hot with the meat and vegetables.