Mentsuyu is litteraly means noodle soup. The liquid diluted with water is used for noodle soup. It contains umami taste from dashi stock and good balance of soy sause and sweetness of mirin. The mentsuyu also can be used as a convenient seasoning because the mixture contais dashi stock, soy sauce, mirin, sake and sugar. There are various recipes of mentsuyu including the ingredients, seasonings' ratios and the taste. There are various kinds of bottles of Mentsuyu in grocery market shelfs in Japan. We often find mentsuyu in recipe generally, that's mean mentsuyu is now national seasoning.
I teach how to make dashi stock in my cooking class for making miso soup, however in fact, many Japanese use instant dashi powder or saches for making miso soup, not makind the dashi stock from the scratch.
We often use dashi stock beside miso soup recipe, such as vegetable mixture "aemono" and savory egg custard. The dashi stock flavor enhances the taste of the dishes because the dashi stock contains rich Umami flavor. When the recipe calls small amount of dashi stock, I would use mentsuyu for instead of fresh dashi stock.
I saw and occationally bought mentsuyu in grocery store in NY and Chicago, I believe it was a Whole Foods Market, but I also made the seasoning at home.
Home made mentsuyu is much more flavorful, rich in umami,fresher taste and less expensive than the premade bottle.
Here is the recipe for about 200 ml Mentsuyu
Mentsuyu
Ingredients for about 200 ml
Soy sauce 6 Tablespoons
Mirin 6 Tablespoons *can be replace to 2 Tablespoons of Honey Sake 1 Tablespoon Sugar 1 teaspoon Bonito flakes 5g or a light handful Dried sea kelp 2cm or 2 g
Add all the ingredients into a microwave-safe container. Mix and submerge all the dry ingredients into the liquid.
Microwave 600w for 4 min without plastic wrap.
After the liquid become room temperature, Drain them over a sieve. Squeeze well from the dried ingredients.
This dark liquid is Mentsuyu sauce.
Soba/ Udon noodle soup for 1 person
Mentsuyu sauce 2 Tablespoon
Water 150 ml
Cooked soba noodle or Udon noodle
Mix mentsuyu sauce and water in a small pot and bring them to a boil.
Prepare cooked noodle in a bowl. Add warmed diluted mentsuyu over the noodle.
Cooked scallions, eggs, fried tofu are go with the noodles.