Duck sauce is a light orange color, sweet and tangy sauce. It usually comes in a small 2 inch x 1 inch clear pouch that you can find them in every Chinese take out restaurants in America. It is without doubt an American all time favorite. No egg roll is completed without this sauce. So why is duck sauce called duck sauce? Clearly there is no duck ingredient inside?!
To most Chinese, this sauce is known as "sour plum sauce" (酸梅醬) and it is being served with - you guess it - roast duck. In Hong Kong and most part of southern China (Guangdong, mainly), whenever you purchase or order a roast duck, it will come with this sauce. It is recommended that you dip your duck piece into the sauce, for better taste and most importantly, it helps to mask out the "gamy" duck flavor as well as the "fat". The sauce is made with pickled plum (a small type of green color plum), sugar, vinegar and sometimes pickle bits too.
So why is it called "duck sauce" and not "plum sauce"?
When I was researching for the Chinese take out cooking video series (www.chopstickbowl.com), I made a note to research this cause I am puzzle by its name too. After talking to a lot of Chinese chefs, I finally understand where it comes from. It turned out that in the early days, Chinese cooking ingredients are limited and hard to find, so instead of pre-make all their sauces, most chefs would rather cook them upon order. Then one day, a dining patron dipped his egg roll with the sweet and sour Chicken sauce and loved it so much that he ordered this on every return visit. It all went well until one day, the chef was sick, so no sweet and sour Chicken sauce (you see the only person who knows how to make the sauce is the chef, no one else). The manager did not want to disappoint this regular, so when he saw the plum sauce that he got with his roast duck earlier, it gave him an idea. He decided to serve his regular's egg roll order with this plum sauce. He told the regular that this was a special sauce, just for egg roll dipping and he was the first one to try it. The regular tried it and told the manager that he loves it. From that onwards, this restaurant began serving their egg roll with this plum sauce, but due to their limitation on English language, they had trouble translating the plum sauce name. The manager said since the sauce is primarily used for eating duck, so let's called it "duck sauce". And so this plum sauce is now called "Duck Sauce" - no duck inside, just associated with eating duck.
With this sauce becoming so popular, few years ago, one of the sauce suppliers decided to modify the sauce to a much sweeter, less sour and lighter color sauce, and started packing them into small pouch. Now there are over 5 factories in the US manufacturing this "duck sauce" and you can also find them in a jar in local supermarket. It definitely has become one of the Chinese take out icon, next to the Chinese pagoda take out box.
But mind you, if you want to buy this "duck sauce" from the Asian grocery, it is usually labelled as "plum sauce" - not "duck sauce". Be sure it is orange in color and has jelly like texture. There is another "plum sauce" that is brown and salty. It is made of pickled plum mixed with brown bean paste, very salty and suitable for steaming dishes like pork rib tips and sometimes fish.