1Preheat the oven to 300°F.
2Set a wide pot or braising dish over medium-high heat, add a drizzle of oil and cook the bacon until crisp; transfer to a shallow bowl, leaving the drippings.
3Brown the beef in the drippings on all sides, working in batches, sprinkling with salt and pepper in the pan and setting it aside on a plate as it gets browned and crusty on the edges. Add the onion to the pot and cook until golden; add the garlic and cook for another minute or two.
4Add the beef stock to the pan, scraping up any browned bits on the bottom. Return the beef to the pot, pour over the beer, stir in the brown sugar and balsamic vinegar and add the sprigs of thyme. Cover and cook for 2 1/2-3 hours, until the meat is very tender. Remove the lid, and if the gravy is too thin, set the pan on the stovetop and simmer uncovered until it thickens.