Preparation

• Stir together the hot water, kansui, and salt in a medium bowl until dissolved.
• Put the flour into a food processor fitted with the dough blade; pulse a few times. With the machine running, drizzle in about 3/4 cup of the kansui mixture. Stop to squeeze the dough and incorporate any clumps of dry flour. Continue mixing in the water 1 teaspoon at a time just until the dough forms small, distinct balls that, when squeezed, meld into a smooth mass.
• Knead by machine for 3 minutes, then finish kneading by hand for 2 minutes.
• Shape the dough into a smooth square, wrap in plastic, and let rest for at least 1 hour or refrigerate for up to 1 day.
• Divide the dough into four pieces. Using a pasta machine, pass each piece through the rollers, starting with setting 1 and working through to setting 5. Coat the dough sheets well with potato starch to prevent sticking, and then pass noodles through the thin-width cutters. Dredge the noodles evenly with more potato starch.
• Boil immediately, or wrap well and refrigerate for up to 3 days.

Note: To make kansui in a dry form, thinly spread 1/4 cup baking soda on a foil-lined cookie sheet. Bake for 1 hour at 250˚F. Let cool and store in a tightly-sealed glass jar. To make ramen noodles, stir 1 Tbs. dry kansui powder into 1 cup of water until completely dissolved, before adding the salt.