Tosazu (tosa vinegar) (土佐酢)
Tosazu is a mixture of sanbaizu (vinegar, soy sauce and sweet cooking rice wine mixed in roughly equal proportions) and soup stock made from dried bonito. With a good flavor of soup stock as well as less vinegar and milder taste, tosazu is used for aemono (sliced fish, shellfish and/or vegetables mixed with a sauce such as miso or vinegar) with bland seafood.
Due to its use of soup stock made from dried bonito, Tosazu was named after Tosa, a region famous for bonito.
A cup of nihaizu (vinegar and soy sauce mixed in roughly equal proportions) or sanbaizu together with 5 to 10 grams of sliced dried bonito will produce three-fourths cup of tosazu.