Everyone has heard of the company Kikkoman, mostly for their soy sauce that can be found on any table in an Asian food restaurant. I bet your soy sauce in your house is Kikkoman. They also have a lot of other type of sauces to use for various uses. I picked up a bottle of this ready to use base for cold noodles. If you are going to eat Somen noodles and you are going to serve them cold in a bowl, then this is the sauce you want.
That day Ms. Noodle and I got a bag of Some noodles and I saw this bottle that I used once before when I was invited over for a cook out with Japanese baseball coaches cooking dinner. It was a delight.
Just boil some water to get the noodles to the desired tenderness that you like and serve them in a bowl (with out water or liquids in bowl). Let them cool off for serving and then, using this bottle of "Somen Tsuyu" pour it on the noodles to the desired amount.
It adds a great flavor to them, I think they use various fishy things and some soy sauce but it is a great way to eat cold noodle. I recommend getting this for Somen noodles if you want to not serve hot noodles. It might be good on hot noodles, I don't know!