Take the salmon out of the fridge and keep it at room temperature while you are making the teriyaki sauce
Wash and finely chop the green onions and set them aside for the very end as a garnish
Peel the garlic. Grate or finely mince the garlic and set it aside
Grate the ginger or finely mince it. If you are mincing it, make sure they are as small as possible. Alternatively, you can use 1 slice of ginger, and discard it after the sauce has finished cooking. Set the ginger aside
In a small bowl, mix the rest of the teriyaki sauce ingredients (soy sauce, sugar, rice wine vinegar, water) minus the sesame oil. Set it aside
In another small bowl mix the corn starch and cold water together and set aside
Set the stove to medium-low heat and set a small pot over it. Add a bit of oil and wait until it gets hot and shimmery. and toast garlic and ginger in oil for approx 1-2 mins or until light brown
Add the garlic and ginger into the pot and toast it for 1-2 minutes until it is light brown in color
Once the garlic and ginger are brown, add the sauce ingredients you previously mixed in a small bowl into the pot. Keep stirring the sauce and cook for 3-5 mins until it starts to bubble
Once the sauce starts to bubble, mix the corn starch slurry again in the small bowl (the corn starch may separate and settle on the bottom of the bowl) and pour it into the sauce, Keep stirring until the sauce has thickened
When the sauce has thickened, turn off the heat and mix in the sesame oil. Put a lid on the pot to keep the sauce warm while we cook the salmon