In a large frypan over medium-high heat brown the roast on all sides, about 10 minutes. Place roast into a large roasting pan. Pour beans, beer and tomatoes over roast. Arrange onions, eschallots, garlic, bay leaves and sprigs of rosemary around the roast and season with salt and pepper.
Cover and bake for 4 hours. Raise the temperature to 220 degrees C and roast 1 hour more.