for the sauce: 3/4 cups smooth peanut butter 3 tablespoons soy sauce 2 tablespoons rice vinegar or white wine vinegar 1 tablespoon lime juice 1 small garlic clove -minced cayenne pepper to taste 1/2 cup hot water 12 ounces pasta -i.e. rotelle, -penne, farfelle 2 carrots -cut into thin -slices on a -diagonal 1 1/2 cup broccoli florets 1/2 pound snow peas -trimmed and cut -crosswise into -1-inch pieces 4 scallions -thinly sliced