In a medium size bowl, whisk together teriyaki sauce, soy sauce, brown sugar, garlic, olive oil and rice vinegar until well combined.
Place salmon pieces in the teriyaki mixture and coat completely. Cover the bowl with plastic wrap or foil and place in the refrigerator to marinate for 20-30 minutes.
Preheat oven to 400 degrees F. Line a baking sheet with parchment paper. Arrange salmon (not touching) on the baking sheet and bake for 12-16 minutes, reserving the sauce. Cooking time will depend on size and thickness; it's done when the salmon is a light pink color and is tender and flaky.
While the salmon is baking, pour the sauce into a small saucepan and bring to a boil over medium heat. Reduce heat to low and stir often, until sauce is reduced and thickened; about 4-5 minutes. You will know it's done when it coats the back of a spoon. Set aside.
Remove salmon from the oven. Pour thickened sauce over each piece.
If desired, broil for 1-2 minutes after the sauce is painted on to brown and caramelize the sauce.
Garnish with sesame seeds and green onion immediately before serving.