Cook the sausage in a 10-inch skillet over medium-high heat until well browned. Pour off any fat.
Add the pepper and onion to the skillet and cook until the vegetables are tender-crisp, stirring occasionally. Stir in the soup, mustard and milk and heat to a boil. Reduce the heat to low. Cook for 10 minutes or until the sausage is cooked through, stirring occasionally.
Place 1 sausage link into each roll. Divide the pepper mixture among the rolls.
Ingredient Note: Different brands of Italian sausage can have anywhere from 4 to 6 links in their 1-pound package. If the package has more than 4 links, cut them into 2-inch pieces and cook as directed above. Then, divide the sausage and pepper mixture among the rolls.