Ponzu
A citrus-based dressing or dipping sauce that is common in Japanese food. Thin in consistency and brown in color, this substance is made by boiling mirin [1], rice vinegar, fish flakes, and seaweed over heat. The liquid is then strained and mixed with yuzu [2] juice. Ponzu has a tart flavor and is used as a dressing for grilled meats and as a dip for vegetables and sashimi, among other things.

Source [3]