Ponzu sauce is a traditional dipping sauce used in Japanese cuisine. Ponzu is made by boiling mirin, rice vinegar, bonito flakes, seaweed (konbu).
You can purchase ponzu sauce in any Japanese or most any other well-stocked Asian grocery store. Alternately you can find Ponzu Sauce online at Amazon.com.
If you don't have the fish flakes or kombu, try adding 2 - 3 teaspoons fish sauce Combine all ingredients and allow to stand at room temperature over night. Strain if using the fish flakes and kombu. Use or store refrigerated.