[edit]Geez -- I looked for this thread and couldn't find it to link to the poster above me. Praise be to the moderators[/edit]
You may be able to find "pot sticker sauce" or "dumpling sauce" or "gyoza sauce" depending on what variety... but I never buy this pre-mixed.
Here's my basic recipe, easily doubled or more
1 tbs soy
1 tbs rice wine vinegar
1 tsp sesame oil (the dark stuff)
1 tsp sugar
to this, you can doctor it up with one or more of
1/2 tsp grated fresh ginger (no powder!) -- I consider this essential but I've done without it
1 clove garlic grated on a microplane
1 scallion or several chives or garlic chives, slivered
a generous squirt of sriracha, chile oil or chile paste or some red pepper flakes
It's really quite flexible. I've used chinese black vinegar instead of rice(decrease the sugar), thick soy a.k.a. kecap manis instead of soy (skip the sugar completely). The point is to balance the sharp (vinegar, salt, ginger, chile) with the smooth (sesame oil, garlic, sugar). It should taste good on its own, but keep it simple if you want the flavors of the dumplings, etc. to shine through.
What is patriotism, but the love of good things we ate in our childhood?
-- Lin Yutang