Roast Beef with Mashed Potatoes

1 cup of cabernet sauvignon
2-4 cups beef broth (enough to cover roast)
1 white onion (sliced)
2 bay leaves
2 tbsp balsamic vinegar
2 tbsp black pepper
Add a tbsp of olive oil & brown the roast beef on all sides, inside a cast iron pan. Add in all of the rest of ingredients. Bring to a boil & then turn down to low for 4-6 hours.