Pre-heat the air fryer to 325F and spray the grate with non-stick cooking spray.
Add the brats to the air fryer basket and spray with olive oil cooking spray.
Air fry for 9 minutes, shaking halfway through. Remove from tray with tongs when done.
While the brats are cooking, cut the hoagie rolls, dice the onion, and drain the sauerkraut.
Line the cut rolls with sauerkraut and nestle the cooked brats into the bun. 2-3 at a time, add the sandwiches to the air fryer. Turn up to 400F and air fry for 3-5 minutes, toasting the bun and sauerkraut.
Finish with a drizzle of mustard and diced white onion. Enjoy with a cold beer or drink of choice.
Notes
A bratwurst should reach an internal temperature of 160F.
You can store leftover bratwurst in an air-tight container in the refrigerator for up to 4 days. When ready to eat again, simply reheat in the air fryer at 325F for 3-5 minutes.