Prep the meat and remove any excess fat from it. Place the meat in a resealable plastic bag and Worcestershire sauce, garlic, and salt and pepper to taste. Refrigerate overnight.
Once you are ready to cook the asado, remove meat from the plastic bag and transfer the leftover marinade to a bowl. In a large pan heat the oil over medium-high heat. Once the oil heats add the sugar to the center of the pan. Do not stir; let it dissolve and cook until it turns brown. Once it does, add the meat and sear on both sides.
Add the meat marinate, and continue cooking for 15 minutes. Add water and continue cooking until it comes to a boil. Once it does, cover for 10 minutes.
Add the carrots, green peppers, onions, bay leaf, oregano, beef bouillon and beef stock, and adjust heat to medium-low. Cook for 3 hours at this temperature.
Remove meat from slow cooker, and pour the remaining marinade and vegetables in a blender and and purée into a sauce, until all the ingredients are smooth. Pass the sauce through a strainer.
Once you are ready to serve, place meat on cutting board and cut into ½-inch pieces. Cook for 5 minutes in its own sauce from the blender, over medium heat.