This is a notional recipe for a dumpling sauce. It goes great with fried potstickers.

Mix well:

1 Tbsp soy sauce
1 Tbsp mirin (or tempura sauce)
1 Tbsp rice vinegar
1/2 Tbsp sugar
Dash of spicy sesame oil

Top with:
Sliced green onions

I have no idea if these are the right proportions, so start with this and just adjust according to your taste!