1Place chicken pieces in a bowl and chill.
Finely grate ginger into a fine sieve placed over a small bowl. Firmly press out all the liquid with the back of a spoon. (You should have about 1 1/2 Tablespoons liquid). Add mustard, vinegar, sesame oil, sugar and soy sauce to the ginger juice and whisk until creamy; set aside.
Bring 4 qt. salted water to a boil. Blanch snow peas in boiling water for 1 minute. Remove them with a slotted spoon and transfer to a colander. Rinse under cold running water and set aside. Return the water to a boil, add pasta and cook until just tender, about 8-10 minutes or according to package directions. Drain and rinse with cold water; set aside. Combine celery, bell pepper, scallions and the reserved chicken, snow peas and pasta in a large bowl. Add dressing and toss to coat. Taste and adjust seasonings with salt and pepper. Transfer to a serving platter and garnish with sesame seeds. Serve immediately.