Start by peeling your ginger and garlic. Chop the aromatics into very fine pieces.
Next, drizzle in 1 tablespoon of oil and drop in your finely chopped garlic and ginger. On low heat, let the garlic and ginger bloom and become fragrant.
After about 3 minutes, add in equal parts of sake, mirin, and soy sauce. Bring to a boil and let the alcohol cook off. This will take about 5 minutes on medium heat.
Once the sauce has reduced by about 1/3, mix together the corn starch and water in a small bowl.
Drizzle in your corn starch slurry and give it a mix. Your teriyaki sauce should become nice and thick.
Finally add in about 1 tablespoon of sesame seeds. Stir to combine and once the sauce is cooled store in an air tight jar. Keep in the fridge until you are ready to use!