Preparation Cook scallion whites, vegetable oil, red pepper flakes, sesame seeds, and pepper in a small saucepan over low heat, stirring occasionally, until oil is sizzling and scallions are golden brown, 12-15 minutes; let chili oil cool in saucepan. Meanwhile, cook noodles in a large pot of salted boiling water until al dente; drain. Rinse under cold water and drain well. Whisk tahini, vinegar, soy sauce, sesame oil, sugar, and 2-3 tablespoons chili oil (depending on desired heat) in a large bowl; season with salt. Add noodles and toss to coat. Top with scallion greens and drizzle with more chili oil.
Preparation Cook scallion whites, vegetable oil, red pepper flakes, sesame seeds, and pepper in a small saucepan over low heat, stirring occasionally, until oil is sizzling and scallions are golden brown, 12-15 minutes; let chili oil cool in saucepan. Meanwhile, cook noodles in a large pot of salted boiling water until al dente; drain. Rinse under cold water and drain well. Whisk tahini, vinegar, soy sauce, sesame oil, sugar, and 2-3 tablespoons chili oil (depending on desired heat) in a large bowl; season with salt. Add noodles and toss to coat. Top with scallion greens and drizzle with more chili oil.