Preheat a grill on medium heat and the oven to 400 degrees.
Mix the potatoes with garlic powder, paprika, salt and pepper, and half of the olive oil in a bowl. Place on a foil lined baking sheet and cook in the oven for 15 minutes, then stir the potatoes around and cook for another 15 - 20 minutes or until golden brown and tender.
For grilling the sausage: Cook the sausage on both sides to an internal temperature of 150 degrees using a thermometer. If using an oven: Place sausage on a foil lined baking sheet; cook for 10 minutes flip and cook another 5 minutes or until internal temperature of 150 degrees. Remove from oven and set aside.
In the meantime in a nonstick pan heat the remaining oil on medium heat; saute the onion and pepper for 6 - 10 minutes, or until they are soft and golden brown.
Slice the sausage into chunks and miix with the potatoes, onions, and peppers. Serve with mustard and crusty bread.