In a mixing bowl, whisk together the low-sodium soy sauce, water, brown sugar, rice vinegar, minced garlic, grated ginger, and sesame oil until the sugar is dissolved.
Place the salmon fillets in a shallow dish and pour half of the teriyaki sauce over them. Allow the salmon to marinate for at least 15 minutes.
Preheat your air fryer to 400°F (200°C) for about 5 minutes.
In a small bowl, mix the cornstarch with 1 tablespoon of water to create a slurry.
Place the marinated salmon fillets in the air fryer basket, skin-side down. Cook for 10-12 minutes.
While the salmon is cooking, pour the remaining teriyaki marinade into a small saucepan. Bring it to a simmer over medium heat, then stir in the cornstarch slurry. Continue to cook until the sauce thickens, about 2-3 minutes.
Once the salmon is done, drizzle the thickened teriyaki sauce over the fillets. Serve with steamed rice and your favorite vegetables.