Note: you may need to make this recipe in 2-3 batches if your air fryer has a smaller capacity.
Cut the peppers and onions into wedges that are about 1-inch (2.54 cm) thick. (If you cut them too thin, they're more likely to burn!)
Put the onions and peppers in a large bowl. Stir in the olive oil, red wine vinegar, dried basil, dried oregano, salt, and pepper.
Spread the onion and pepper mixture out on two air fryer trays. Drizzle any olive oil mixture left in the bowl on top of the veggies. Put the trays in your air fryer.
Air fry the peppers and onions for 6-7 minutes at 400°F (200°C). Then switch the position of the trays in the air fryer and air fry for 6-7 more minutes at 400°F (200°C).
Take the trays out of the air fryer. Flip and stir the peppers and onions. Place two fresh Italian sausages on top of the veggies in each tray. Put the trays back in the air fryer.
Air fry for 20 minutes at 400°F (200°C), switching the position of the trays in the air fryer after 10 minutes. (Stir the veggies if needed.)
Check the sausage with a meat thermometer after cooking. If you used chicken or turkey sausage, it should have reached a safe minimum internal temp of 165°F (74°C). All-pork Italian sausage should reach a minimum safe temp of 160°F (71°C).
Let the sausages rest for 10 minutes before serving. If you'll be serving the sausage and peppers in submarine rolls, toast them while you wait. Toast the rolls, cut side up, for 2 minutes in an air fryer preheated to 400°F (200°C).
To serve: split each sausage in half lengthwise. Divide the peppers and onions between 8 toasted grinder rolls, and top with a sausage half. Spoon warm marinara sauce over the Italian sausage grinders, and sprinkle with Parmesan cheese.