Rinse off your roast and place in the crock pot whole. You can sear it in prying pan if you want but it is not necessary.
Add one onion, finely chopped, the beer, dried cilantro, cumin, chili powder, one can of the green chilies, the Worcestershire sauce, 2 cloves of garlic, and the juice of one lime.
Put crock on low or high depending on how much time you have, its done when it is fork tender to shred easily.
When meat is ready, grate your cheese, slice up your second lime into 6 wedges, slice up your avocado, chop your cilantro, finely chop your second onion and open the second can of green chilies. (you can also use green taco sauce in place of the second can of green chilies)
Warm up your tortillas in the microwave, then take two corn or one flour tortillas, using tongs place a bit of the meat inside each taco shell, layer the cheese, cilantro, green chilies, onion and an avocado. Top with the juice of a lime wedge. You can also add sour cream if you want but they are good without it. Enjoy!!!