Bring 4 quarts of water to boil in a large pot. Add salt and pasta and cook according to package instructions for al dente. Reserve 1 cup cooking water. Drain pasta in colander, rinse with cold water, drain again and transfer to large bowl. Add toasted sesame oil and toss to coat.
In a separate large bowl, whisk peanut butter, soy sauce, vinegar, hot sauce, ginger and sugar; adding pasta water as needed to thin. Add cooled pasta, mango, red peppers, scallion, and cilantro to peanut sauce and toss to coat. Serve at room temperature.