Beef with Beer and Onions

4 pounds chuck roast
1 large onion sliced
1 4 oz. jar horseradish
1 15 oz. can beef broth
1 bottle good dark beer (Black Butte Porter...Yummy)
1 teaspoon fresh thyme
1 1/2 tsp. kosher salt
1/2 tsp. pepper
Cut the roast into 6 - 8 chunks. Brown the chunks in a little oil. Add the remaining ingredients. Bring to a boil. Reduce heat. Cover and simmer for 2 - 3 hours until the meat is very tender and falls apart. If the braising liquid is too thin, you can remove meat and reduce the sauce until it thickens.