Traditional Scottish Stovies

Name: Traditional Scottish Stovies
Prep time: 10 min
Cook time: 50 min
Total time: 1 h
Cuisine: European, British
Ingredients: 1 tablespoons lard (or beef dripping); 2 medium onions (or 1 large onion, skinned and roughly diced); Optional: 4 tablespoons dark beer (or stout); 4 ounces roast beef (cold and diced); 1 1/2 pounds potatoes (peeled and quartered); Salt (to taste; Pepper (to taste); 1 1/4 cups beef stock (or leftover gravy); Vegetables (any that you have leftover from the day before)