Sprinkle both sides of the salmon with kosher salt. Let the salmon sit for 5 minutes while you mix the spices in step 2.
In a small bowl, mix mayo, avocado oil, garlic powder, paprika, and black pepper until combined.
By now you should see excess water pooling up on the salmon. Pat dry and flip the filet over, then run a sharp knife over the salmon skin to draw out moisture and remove excess scales (skip this step if are using skinless salmon), then pat both sides of the salmon completely dry with a paper towel. Place the salmon skin side down and rub the marinade on the flesh side only.
Spray the air fryer basket with a neutral oil spray. Place the salmon side down and air fry at 400F for 8-12 minutes depending on the thickness of the salmon. After the 8 minutes of cooking, check the salmon in 1 minute intervals after 8 minutes until the salmon reaches 145F.
