Place separated slices of meat in a gallon plastic bag with a zipper, and set it aside.
In a large bowl, combine all of the other ingredients: soy sauce, brown sugar, sambal oelek, garlic, red pepper flakes, and black pepper, and mix it until fully combined.
Pour the marinade mixture directly over the beef into the plastic bag. Zip the bag up and squeeze and turn it to ensure all of the meat gets covered with the marinade.
Place the bag in the refrigerator and allow it to marinate at least 2-3 hours, or overnight.
Spray the air fryer with non-stick spray. Place the meat directly on the tray, in ONE single layer. Try not to overlap the meat too much.
Close the air fryer, and press the dehydrate button (temp should read 150 degrees). Set the time to 1 ½ hours, and close.
After 45 minutes, open the air fryer and flip the meat over. Close and continue to cook the additional time.
Remove the beef jerky from the air fryer and enjoy, or place in an airtight container or bag. Beef jerky can be stored in a cool dry place, for up to one week.
