Cold Rice Noodles with Peanut-Lime Sauce

Peanut dressing
3 tablespoons Asian fish sauce
3 tablespoons rice vinegar
9 tablespoons lime juice
3 tablespoons soy sauce
1 one-and-a-half inch chunk ginger, peeled and sliced
6 tablespoons natural unsalted peanut butter
1 tablespoon toasted sesame oil
Pinch of cayenne