1/2 cup soy sauce
1/4 cup mirin (or 1/4 cup rice vinegar + 2 tbsp sugar)
2 tbsp brown sugar (or honey)
2 cloves garlic, minced (optional)
1 tsp fresh ginger, grated (optional)
1 tbsp cornstarch
2 tbsp water
In a small saucepan, combine soy sauce, mirin, brown sugar, garlic, and ginger.
Bring to a simmer over medium heat, stirring until sugar dissolves.
In a separate cup, whisk cornstarch with water until smooth.
Slowly whisk the cornstarch slurry into the simmering sauce.
Simmer 1–2 minutes, stirring, until thickened.
Remove from heat and cool slightly before using.
Store in the refrigerator up to 1 week (reheat gently to use).