Slice bell peppers and onions into long, thin strips.
Add peppers and onions into the basket or tray of air fryer, cook at 320℉ for 10 to 12 minutes. Halfway through toss/stir.
Remove peppers and onions from the air fryer and set aside.
Next up, place Italian sausages in the air fryer in a single layer.
Air fry the sausages at 370℉ for 10 to 12 minutes, flipping them halfway through the cooking process.
Slice open the buns, spread 1 to 2 tablespoons of marinara sauce on the inside.
Place a cooked Italian sausage on top of the marinara sauce, top with cooked peppers and onions.
Give a hefty sprinkle of mozzarella cheese and additional marinara sauce.
Cook at 350℉ in the air fryer for 2 minutes or until the cheese melts.
Garnish with dried oregano, parsley and red pepper flakes.