Using thin (no more than ¼ inch thick) slices of sirloin steak, cut any larger pieces into ¼-inch long strips. Cut against the grain for the most tender pieces. Be sure to trim off any excess fat or tough gristle pieces from your beef. Place your beef strips in a bowl and set aside.

In a small mixing bowl, make your marinade by adding the low-sodium soy sauce, Worcestershire sauce, brown sugar, garlic powder, onion powder, black pepper, and red pepper flakes. Stir to combine and pour into the bowl with the beef strips.

Coat all the beef with the marinade, cover the bowl with plastic wrap, and refrigerate for a minimum of 8 hours, but overnight is best.

Once the beef strips have marinated, drain all the liquid from the beef. Place the beef onto a paper towel-lined tray and use a second paper towel to pat the beef strips dry very well.

Place half the beef strips into the basket of the air fryer in a single layer, being sure that you have a little space between the strips. Cover the remaining beef strips with plastic wrap and refrigerate until ready to air fry.

Set the air fryer to 200°F for 60 minutes (that is the maximum amount of time the 6.8-quart Cosori brand air fryer could be set to), then once that time is up, you will set your air fryer for another 60 minutes at 200°F. You will need to note that depending on the thickness of your beef strips, and the power of your air fryer, you may have to add a little extra time to your air fryer time when making your beef jerky.

Once your beef jerky is done, remove it to a container and repeat step 6 with the remaining half of your marinated beef strips.

Once your beef jerky is done in the air fryer, you can store it in an airtight container on the counter for up to 2 weeks. You can freeze your beef jerky for up to 6 months for longer storage.