Cook 8 ounces dried udon noodles as the label directs; drain and let cool. Grill 1 bunch scallions over medium-high heat, turning, until charred, 3 minutes. Let cool and slice. Whisk 3 tablespoons each tahini, soy sauce and rice wine vinegar and 2 teaspoons each toasted sesame oil, sugar and grated ginger in a large bowl. Stir in 1 to 2 tablespoons water to make a smooth sauce. Add the noodles, 2 cups bean sprouts and 1 cup each cooked edamame, shredded carrots and julienned snow peas; toss. Sprinkle with toasted sesame seeds.
Photograph by Bobbi Lin