(Note: if you are unsure about how much meat may be on your short ribs, it may be worth asking your butcher how many pounds he/she thinks you need for the amount of people you are feeding, since they all differ.)
The night before or the morning of, heat olive oil in a large skillet over medium-high heat. Once hot, add short ribs and sear on all sides, just for about 1 minute, until golden and brown. Remove and place in the crockpot. In a small bowl, combine salt, pepper, paprika, onion powder, garlic powder, chili powder and cumin and mix. Sprinkle over short ribs, then pour beer in to the crockpot. Cook for about 8 hours on low, or until meat is falling off the bone. If able to, rotate short ribs once or twice during cooking.
Once finished cooking, remove with kitchen tongs and set on a large place. Let cool until you can touch them, then remove the meat from the bone.
In a large bowl, combine cabbage, lime zest and juice with a pinch of salt, tossing well with your hands to coat.
To serve, warm tortillas first, then assemble tacos with meat first, then cabbage, then crumbled cheese. Enjoy!