When I am making stir fry, this is my go-to sauce. I make a bunch at a time and then keep it in a jar in the fridge.
1/3c sesame oil
2/3c soy sauce
Add spices to taste:
Brown sugar (approx 2 T)
Crushed Red Pepper (approx 1t)
Ginger (approx 1/2t)
Garlic (approx 1t)
Sesame seeds (optional)