Remove stems and seeds from dried chili peppers. Place chili peppers in a small saucepan and add water.
Add more water to cover if necessary. Bring chili peppers to a boil and simmer until softened, about 10 - 15 minutes.
Add chili peppers, about a 1 cup of their water, cloves, peppercorns, cumin, garlic and onion to blender.
Blend on high until well blended. Use a strainer to remove any fibrous pulp or seeds.
Rub adobo all over chuck roast and place in slow cooker. Place bay leaf on top and cover. Set slow cooker to low and cook for 8 - 10 hours, or longer. Meat should be buttery tender and pull easily when cooked though.
To serve, heat corn tortillas in skillet or microwave. Place barbacoa on tortillas topped with diced tomatoes, chopped fresh cilantro, diced onion, sliced avocado and mild salsa verde. Serve with fresh lime slices and enjoy!
