In a saucepan, mix the soy sauce, ¾ of the water, garlic, ginger, honey, and brown sugar.

Heat the saucepan on medium heat and stir constantly until the sugar dissolves and the mixture thickens slightly.

In a separate bowl, mix the cornstarch with the remaining ¼ water to make a slurry (thick mixture).

Pour the cornstarch slurry into the saucepan and continue stirring until the sauce becomes thick and glossy, about 2-3 minutes.

Remove the teriyaki sauce from heat and let it cool down.

Place the salmon fillets in a shallow dish or resealable plastic bag.

Pour the cooled teriyaki sauce over the salmon, making sure it's evenly coated.

Cover the dish or seal the bag and refrigerate for at least 15 minutes (up to 1 hour) to marinate.

Take the marinated salmon out of the fridge and place it in an air fryer-safe dish.

Air fry the salmon for about 12 minutes, or until it's cooked through and flaky.

During the last 2-3 minutes of cooking, brush the reserved teriyaki sauce over the salmon if you want a caramelized glaze.

Carefully remove the cooked salmon from the air fryer.

Sprinkle sesame seeds and thinly sliced scallions over the salmon.

Serve the teriyaki salmon hot, over steamed rice or with your favorite side dishes.