noun
bonito-flavored vinegar dressing
A vinegar-based dressing or sauce flavored with bonito (katsuobushi), commonly used in Japanese cuisine, especially in Tosa region dishes.
刺身に土佐酢をかけて食べる。
I eat sashimi with bonito-flavored vinegar dressing.
この和え物には土佐酢がよく合う。
This dressed dish goes well with bonito-flavored vinegar dressing.
三杯酢 is a sweet vinegar dressing made with equal parts vinegar, soy sauce, and mirin, without bonito flavor.
From 土佐 (Tosa, the old province name for present-day Kōchi Prefecture) and 酢 (vinegar). The name reflects its origin in Tosa cuisine, where bonito is a specialty.