Preheat your air fryer to 400 degrees. Set it for 11 minutes. You'll need to check with a thermometer to see if they're ready earlier. It needs to get to 145 degrees.
Pat the salmon dry with paper towels. Salt and pepper the salmon to taste.
Take a cup and fill it with olive oil, soy sauce, dijon mustard, brown sugar, garlic powder, and onion powder; stir the mixture.
Use a brush to cover the salmon liberally and on the sides.
Set the salmon in the air fryer, and be sure they aren't touching.
Cook the salmon for up to 11 minutes. The timing depends on the thickness of the salmon filets.
Transfer to a plate, and garnish with lemon slices if you like.