Place onions and peppers on a large foil-lined baking sheet.
Drizzle veggies with olive oil and balsamic vinegar. Sprinkle with Italian seasoning, salt and pepper; toss to coat.
Nestle sausages between veggies. Poke each sausage 5-7 times with a wooden toothpick. Bake in the oven for 20 minutes.
Meanwhile, slice each roll in half and lightly butter the inside of each roll.
After sausage and veggies have cooked for 20 minutes, take them out of the oven. Place the hoagie rolls, open faced, on top of the veggies and return the pan to the oven. Increase the heat to broil; cook for 2-4 minutes until the rolls are toasted and golden brown. (Watch closely so they don’t burn.)
Place 1 sausage into each roll and top with veggies Enjoy!