Add all of the ingredients, except the bay leaves, to the bowl of a slow cooker.
Use tongs to gently toss and mix it all together. Then add the bay leaves, and cover. Cook on low for 8-9 hours, or on high for 4-5 hours. The beef should be tender and fall apart easily when shredded with a fork. If it doesn't shred easily, cook it a bit longer.
Remove the beef to a cutting board and use two forks to shred it.
Place the shredded beef back in the slow cooker, give it a stir, and let it absorb the juices.
Serve the barbacoa straight from the slow cooker, or add it to a plate and garnish with chopped cilantro and lime wedges.