Drizzle some oil into a large, heavy skillet or Dutch oven and set over medium-high heat and brown the beef in batches, sprinkling with salt and pepper.
Transfer to a plate or the bowl of a slow cooker.
Add the onion to the pan and cook for 3-4 minutes stirring to loosen and browned bits on the bottom of the pan. Add the garlic and cook for another minute.
Return the meat to the pan (or add the onions to the slow cooker) and add the beer and thyme, and enough water to come about halfway up the meat.
Cover and bake at 325°F for 2 1/2 hours (or on low for 6-8 hours), until the meat is very tender.
