1. Place the sausages in a medium to large size skillet. Add enough water to come halfway up the side of the sausages. Cover and place over a medium heat. Bring to a boil then drop to a medium low heat and simmer until the internal temperature reaches 155º, about 15 minutes.
2. Slowly whisk in Guinness and beef stock. Add mustard, Worcestershire, salt, garlic powder and onion powder. Bring to a boil, whisking constantly. Once the gravy thickens, drop the heat to low, cover and keep warm.