Pour the water into a big pan. Bring to a boil and add the dried thin white noodles (dried sōmen). Boil for 1 minute and 30 seconds.
After boiling, drain the noodles in a colander and quickly run cold water over them.
Because too much starch and salt on the noodles can make them taste slimy, wash them with your hands under cold running water to remove any extra starch.
Drain again. After cooking, 5 1/4 ounces dried noodles becomes about 17 ounces cooked noodles.