Whisk together soy sauce, ginger, garlic, brown sugar, rice vinegar, and cayenne pepper in a small saucepan. Heat on medium heat for 5-7 minutes. We're basically making homemade teriyaki sauce.
In a separate small bowl, whisk together cornstarch and cold water. Add this mixture to the saucepan and whisk together. Cook and continue to whisk just until it starts to boil then remove from heat. Set aside ½ cup for later use.
Add salmon to an oven safe baking dish (scales side down). Generously brush with the teriyaki sauce left in the pan, coating completely.
Place salmon in the oven and bake for 15-18 minutes. Remove from the oven and brush with remaining ½ cup teriyaki sauce that was set aside earlier. Garnish with sesame seeds and chopped green onion. Enjoy!
The skin can be left on for this recipe, since it is baked it will be tender enough that the meat portion will flake right off of the skin itself.
If you are in a pinch, you can use bottled teriyaki sauce, but homemade is always best. The bottled sauce won't give you the sticky coating like you would if you made homemade.
After baking you can easily cut your salmon into filets and serve with your choice of side, we used rice.
You'll know your salmon is done cooking when you are able to poke the center and it starts to flake.