Tosa Vinegar (Tosazu) is a blended vinegar made by mixing vinegar, soy sauce, and sugar in equal parts (1:1:1), known as Sanbaizu, then adding dashi made from bonito flakes. It has a milder, more aromatic flavor than regular vinegar and is often used for fish dishes. The name “Tosa” comes from the Kochi region, famous for its bonito.
When gelatin is added to Tosazu to create a jelly-like consistency, it becomes Tosazu Jure (Tosazu Jelly) — a modern sauce frequently used in Japanese cuisine. “Jure” is derived from the French word gelée, meaning jelly.