Cut up the pork into large pieces (at least 2in cubes). Put into a heavy bottomed pot, adding all the rest of the ingredients, plus water enough to cover (plus another half inch).
Bring pot to a boil, and then lower heat to a simmer. Allow to simmer for an hour.
Crank the heat back up to a boil, and cook off the liquid. Once almost all the liquid has been cooked off, fish out the ginger and chili.
As the liquid reduces it will get deeper an deeper in color (as the sugars from the beer caramelize). Keep an eye on this, you want it to be as reduced as possible, but you don't want the liquid to burn.
Once the carnitas are finished to your liking, allow it to rest while you heat up tortillas, prepare salsas, and get your pickled onions and jalapenos. While the pork is still quite warm, shred it using two forks. If the pork is a little dry for your liking, feel free to add more bacon fat. Serve happy!