The Japanese citrus soy sauce often used as a dipping sauce is ponzu. More precisely, ponzu is a tart citrus sauce, while ponzu shōyu combines it with soy sauce and is the dark, savory condiment commonly sold simply as ponzu.
Ponzu is traditionally made by combining citrus juice—often yuzu, sudachi, kabosu, or daidai—with a seasoned base that may include mirin, rice vinegar, kombu, and katsuobushi. Its bright acidity balances rich and savory foods.
Ponzu is especially associated with nabemono hot pots such as shabu-shabu, but it is also used with sashimi, grilled meat, grilled fish, and tataki. A common mix-up is treating ponzu as identical to soy sauce: soy sauce supplies salt and umami, while the citrus gives ponzu its distinctive sharpness. The word entered Japanese through the Dutch term pons, meaning a fruit-based punch.