Preheat the oven to 300˚F.
Drizzle some oil in a heavy ovenproof pot or Dutch oven set over medium-high heat and brown the roast on all sides, sprinkling with salt and pepper.
Add the onion and cook for 4-5 minutes, until starting to brown. Add the garlic and cook for another minute.
Add the butter, tomatoes, red wine and thyme to the pan, add enough water to come about halfway up the side of the meat, cover and braise for 3-4 hours, or until the meat is very tender.
Pull apart with two forks, discard the thyme stems and serve over pasta or polenta, with Parmesan cheese passed around the table.