1Slice the beef into thin strips, about 0.6 cm thick and 1.2 cm wide.
2In a large bowl, mix brown sugar, soy sauce, teriyaki sauce, onion powder, garlic powder, red pepper flakes, and black pepper. Add beef strips and mix well to coat. Cover the bowl.
3Refrigerate the marinated beef for at least 2 hours.
4Arrange the strips in the air fryer basket in a single layer without overlapping. Cook at 82°C (180°F) for 2 hours.
5Remove pastrami from the air fryer and let it cool. It will firm up as it cools. Serve warm or at room temperature.
6Store beef pastrami in a vacuum-sealed bag or airtight container in a cool, dark place. It keeps for up to 2 months.