Boil the noodles until done (8 minutes or so). Drain and rinse under cold running water. Drain well, then toss in 2 tablespoons soy sauce and 2 tablespoons sesame oil. Cover and chill about 1 hour.
In a small bowl, whisk together sesame paste and 3 tablespoons warm water until smooth. Add remaining 2 tablespoons sesame oil, soy sauce, vinegar, sugar, cayenne, salt and minced garlic.
Just before serving, toss cold noodles with the sesame dressing.
Peanut butter can be used too, but do use Asian sesame oil.