In a large bowl, combine the beef and ingredients for the marinade until fully combined. Cover and marinate in the fridge for 30 minutes or up to 24 hours.
When ready to cook, preheat the air fryer to 400F. Thread the beef, pepper, and onion onto skewers.
Place skewers into the preheated air fryer and air fryer 8-10 minutes, turning halfway through until charred on the outside and tender on the inside.
Notes: Be sure to check your skewers fit into the air fryer, if not, simply place the meat and veggies into the air fryer as is. Check out these 6 inch (will add link) skewers which should fit into most air fryers.