Cut the roast into 3-inch cubes.
Place the meat into a greased slow cooker.
In a blender, combine all other ingredients except the bay leaf.
Blend until smooth.
Pour the mixture over the meat and add the bay leaf.
Cook in the slow cooker on low for about 8 hours (or high for about 5 hours), until the meat can be shredded easily with a fork.
Remove the bay leaf.
Shred beef directly in the slow cooker to soak up the braising liquid. Serve in corn tortillas or flour tortillas as barbacoa tacos, in burrito bowls, or on top of cilantro lime rice. Plate extras with sour cream, pico de gallo, black beans, fajita veggies, or romaine lettuce.