Preheat the oven to 375 degrees F. Cut the bell peppers into ½ inch strips, discarding the stem and seeds and place onto a large baking sheet.

Remove the skin and root of the onion and slice the onion into ¼ inch rounds or slices. Separate the onion layers into rings. Place them onto the baking sheet with the peppers.

Over the peppers and onions drizzle the olive oil, then add the garlic powder, onion powder, oregano, salt, and pepper.

Toss everything together with your hands or tongs , making sure everything is coated evenly.

Place the baking sheet into the oven and bake for 40-45 minutes tossing around with a spatula every 15 minutes until the vegetables are tender and slightly browned. Set aside.

Lower the oven temperature to 350 degrees F.

Over medium heat, grill the sausages until they are cooked through and seared on the outside, this will take about 15 minutes, or until an internal temperature reaches 165°F. Remove them onto a plate until you are ready to assemble the sandwiches.

In the microwave or in a saucepan on the stovetop, warm the marinara sauce.

To assemble sandwiches, place the sausages into the hoagie rolls, top with some marinara (to your liking).Then add the peppers and onions onto each sandwich. Lastly top the sandwiches with about 2 tablespoons of mozzarella cheese.

Bake the sandwiches for 10-15 minutes until the cheese is melted and the bread is slightly crispy. Serve immediately with more marinara sauce for dipping if desired.