Which vinegar commonly seasons the soy-based tare served with gyōza?

The vinegar commonly used to season the soy-based tare served with gyōza is rice vinegar.

Japanese gyōza dipping sauce is commonly made by combining soy sauce with rice vinegar, often with chili oil or rayu added for heat. The vinegar supplies acidity that cuts through the dumpling’s rich pork, garlic, sesame, or vegetable filling, while the soy sauce contributes salt and umami.

Rice vinegar is produced from fermented rice or rice wine and is generally milder and softer than many Western vinegars. That makes it well suited to a dipping sauce eaten in small amounts with delicate wrappers. Chinese dumplings may instead be paired with black rice vinegar, which has a deeper, more assertive flavor.

Recipes are not rigid: some cooks use seasoned rice vinegar, citrusy ponzu, or another vinegar, and chili oil is an additional seasoning rather than a vinegar. Among the listed choices, however, rice vinegar is the standard and canonical answer for Japanese-style gyōza tare.