Cold soba served with Mentsuyu
Mentsuyu Is The All-Around Sauce Used Across Many Japanese Dishes
Mentsuyu — called tsuyu for short — is a versatile, all-rounder sauce used as a broth base for all kinds of Japanese noodle dishes, and in many other foods as well.
The sweet-salty taste of tsuyu comes from a combination of soy sauce, sugar, mirin, and the iconic duo of kombu and katsuobushi, AKA savory dried kelp and bonito tuna flakes.
Kombu and katsuobushi are used to make dashi broth. Some tsuyu recipes call for premade dashi, while other variations cut out the sugar, add sake, or even use shiitake mushrooms.
To make tsuyu, you can boil all the ingredients together, but many recipes suggest boiling the soy sauce, sugar, and mirin to form a base first before adding the dashi ingredients.
This simmered base, called kaeshi or hon-gaeshi, is a sauce on its own. You can even soak your dashi ingredients in it overnight to add a complex, rich, umami flavor to your tsuyu.
Be it store-bought or homemade, the simmering process of making tsuyu yields a concentrated mixture that needs to be diluted before being used as broth or sauce.
Keep in mind that diluted mentsuyu will expire faster than its concentrated form. Hence, it’s best to refrigerate and consume tsuyu within a few days following the dilution.
While store-bought tsuyu lasts three weeks in the fridge after opening, homemade tsuyu concentrate lasts two weeks if refrigerated in an airtight container, right after cooking.