I have watched the guys at PF Chang's many times make this sauce and I have also made it at home...the dipping sauce did not contain any chicken broth....the recipe is as follows with ingredients only no exact measurements:

rice vinegar
chili paste (From the adian store with the green lid)
spicy Asian mustard
soy sauce

Mix all together after adjusting to you taste you finally get it to suit you taste.

Jacque from San Diego