Preheat oven to 275 degrees. Heat oil in a large dutch oven over high heat.
Season meat generously with salt and pepper. Sear meat on both sides, about 2 minutes per side. Remove meat from pan. Lower heat to medium.
Throw in onions and garlic. Stir for 30 seconds. Pour in beer, and add thyme, rosemary, and salt to taste---about 1 teaspoon. (Do not undersalt!) Add meat to pot, put to submerge, and place lid on pot.
Cook in oven for 2 1/2 to 3 hours, or until meat is fork tender and falling apart.
Shred meat with two forks. Serve on dinner plates and spoon juice and onions over the top.