Combine brown sugar, soy sauce, Hoisin sauce, ginger, garlic, lime juice, and red pepper flakes. Stir until sugar is dissolved. Pour half of sauce over salmon and let marinate in refrigerator for 15-20 minutes.
Pour remaining half of sauce in small sauce pan. Bring to a simmer over medium heat and cook until sauce thickens to point when you can drag a spoon across the pan and sauce doesn't immediately fill the void. Remove from heat and let cool.
Place marinated salmon in air fryer and air fry at 375° F for 8-10 minutes, shaking drum half way through to turn salmon bites. Serve salmon topped with reduced sauce (glaze), sesame seeds, and green onions.