In a medium saucepan, combine the soy sauce, brown sugar, rice vinegar, sesame oil, minced garlic, and minced ginger. Whisk everything together until the sugar dissolves.

In a small bowl, mix the cornstarch with water to create a slurry. Gradually add this to the saucepan while whisking.

Bring the mixture to a gentle boil over medium heat to thicken the sauce.

Cut your chosen protein into bite-sized pieces.

In a large skillet or on a grill, cook the protein over medium-high heat until cooked through, about 5-7 minutes.

Once the protein is cooked, pour the thickened Teriyaki sauce over it and stir well.

Let everything simmer together for an additional 2-3 minutes.

Transfer the Teriyaki to a serving dish and garnish with sesame seeds and sliced green onions.