If you want to double this recipe, DO NOT double the ingredients, for the bulk will be too much to work with. Rather, make the dish twice. If you plan to make this for company, cook noodles ahead of time and add bean sprouts and garlic chives when you heat it up. If it is an informal gathering, it is fun to let your guests cook their own noodles. *You can buy premixed tamarind concentrate or make your own tamarind juice. Buy a package of compressed tamarind pulp at any Asian market, cut off 3 tablespoons of paste and soak in 1 1/2 cups of warm water for 20 minutes. Squeeze out the pulp and discard; the remaining liquid is tamarind juice. Store any leftover juice or noodle sauce in a tightly sealed container in the refrigerator or freezer.