Place the roast right in the slow cooker(you can brown it if you like but not necessary if you are short on time)
Add one large onion sliced, 1 tablespoon of cumin, 1 teaspoon of chili powder, 1 tablespoon of dried oregano, 1-2 chipotle peppers in adobo sauce for medium or hot, Juice of 2 limes, 1/2 cup orange juice or juice of 2 oranges, 2 tablespoons minced garlic, 1 teaspoon onion powder, 3 bay leaves, salt and pepper.
Set the slow cooker to 8 hours and walk away!
When the beef is falling apart, shred it in the slow cooker.
Serve with warmed soft corn or flour tortillas, and top with chopped onion, fresh cilantro, or your favorite taco; take your nachos to the next level! (I like to make coleslaw but substitute lime juice for the vinegar, and add chopped fresh cilantro and a finely chopped jalapeño or red pepper for some color and serve it in the tortilla with the meat.