In a bowl, whisk together balsamic vinegar, honey, soy sauce, garlic, black pepper, onion powder, smoked paprika, and red chili flakes.
Place the beef slices in a large ziplock bag and pour the marinade over them. Seal the bag and massage the marinade into the meat. Refrigerate for at least 4 hours, preferably overnight.
Preheat your air fryer to 165°F (74°C). Place the marinated beef slices in a single layer in the air fryer basket, ensuring they don't overlap.
Air fry for about 3-4 hours, flipping the beef slices halfway through, until they achieve a leathery texture.
Once done, allow the jerky to cool before storing it in an airtight container.