Preheat your air fryer to 390 degrees F for about 3 minutes. While it heats up, slice the sausage links into 3/4-inch rounds and cut the bell peppers and onion into strips roughly the same width.

Add the sliced sausage, peppers, and onion to a large mixing bowl. Drizzle with the olive oil, then sprinkle on the Italian seasoning, garlic powder, salt, and black pepper. Toss everything well so the oil and seasoning coat the sausage and vegetables evenly.

Pour the mixture into the air fryer basket and spread it out as much as you can into a single layer. A little overlap is fine, but avoid piling everything in a deep heap or the vegetables will steam instead of caramelize.

Cook at 390 degrees F for 15 to 18 minutes, shaking the basket well at the halfway point. You are looking for the sausage rounds to be browned on at least one side and the pepper edges to have some light char on them.

Check the sausage is cooked through by cutting into one of the thicker rounds. The inside should be fully opaque with no pink remaining. If needed, cook for 2 more minutes.

Serve immediately in toasted hoagie rolls, spooned over creamy polenta, or alongside roasted potatoes. The juices that collect in the bottom of the basket are great drizzled over everything.