In a medium mixing bowl, whisk together the soy sauce, honey (or maple syrup), rice vinegar, sesame oil, minced garlic, grated ginger, and cornstarch (if using) until the mixture is well combined.
Place the salmon fillets in a shallow dish and pour the teriyaki marinade over them, ensuring they are well-coated. Let it marinate for at least 15 minutes (or up to 1 hour for more flavor).
Preheat your air fryer to 400°F (200°C) for about 5 minutes.
Lightly spray the air fryer basket with cooking spray. Place the marinated salmon fillets in the basket skin-side down, leaving space between each fillet.
Cook the salmon in the air fryer for 8-10 minutes, depending on the thickness of the fillets. Check for flakiness and an internal temperature of 145°F (63°C).
Once cooked, carefully remove the salmon from the air fryer. Brush with additional marinade if desired for extra flavor.
Serve the salmon garnished with sliced green onions and a sprinkle of sesame seeds.