Partially freeze the beef for clean slices. Place the trimmed beef in the freezer for 60–90 minutes. You want it firm but not frozen solid. This makes it far easier to slice thinly.

Slice against the grain, 1/8 to 1/4 inch thick. Thinner slices dry faster and have a classic jerky chew. Slicing against the grain keeps the texture tender rather than tough.

Mix the marinade. In a large bowl, whisk soy sauce, Worcestershire, salt, brown sugar, onion powder, garlic powder, smoked paprika, red pepper flakes (if using), vinegar, and 2 tablespoons of the black pepper. Reserve 1 tablespoon of black pepper for finishing.

Marinate the beef. Add the slices to the bowl and toss to coat. Transfer to a zip-top bag or container, press out excess air, and refrigerate for at least 8 hours or up to 24 hours. Longer marinating means bigger flavor.

Drain and pat dry. Remove beef from the marinade and shake off excess liquid. Lay pieces on paper towels and pat dry thoroughly. This step helps the jerky dry evenly and prevents steaming.

Preheat the air fryer. Set to 175–185°F (80–85°C) if your model allows. If your air fryer’s lowest setting is 200°F (93°C), use that and keep a closer eye on doneness.

Prepare the basket. Lightly spray or brush the basket and any racks with oil to prevent sticking. Arrange beef in a single layer with space between pieces. Do not overlap.

Air fry low and slow. Cook for 2 to 3 hours at 175–185°F, flipping every 30–45 minutes and rotating racks if using multiple levels. If cooking at 200°F, start checking around 90 minutes and adjust time as needed.

Finish with black pepper. About 20 minutes before the jerky is done, sprinkle the reserved tablespoon of freshly cracked black pepper over the pieces. This keeps the pepper bright and aromatic.

Check for doneness. Proper jerky should be dry to the touch, darkened, and flexible. Bend a piece: it should crack lightly along the surface but not snap. If it breaks, it’s too dry; if it’s soft and wet, keep going.

Cool completely. Let the jerky cool on a rack for 30–45 minutes. This final drying time helps set the texture and prevents condensation in storage.

Optional safety step. For extra assurance, you can preheat the beef slices in a 275°F oven for 10 minutes to bring the internal temperature to 165°F before air drying. Then proceed with the air fryer at low temp to dehydrate.