Step 1

To make the sauce, in a large bowl whisk together all ingredients; set aside.

Step 2

In a large pot, bring 4 quarts of water to a boil. Add the noodles and cook until tender. Reserve ¼ cup of the cooking water, then drain the noodles. Rinse under cold water and drain again. Add the noodles and 2 tablespoons reserved cooking water to the sauce and toss until coated. Sprinkle with the scallions.