Mock Duck is not a bird; it is a recipe.
There are two main concepts of what “Mock Duck” means; both are completely different to each other. [Ed: See also Northumbrian Duck, which is more elaborate than either of these.]
Asian Mock Duck Skin
This is an Asian food item meant to look like brownish duck skin with nodules on it. It is used as an ingredient in dishes; it’s not really something you’d eat on its own.
It is made from gluten (normally wheat gluten, aka Seitan), that is rolled out, and pressed so that it has indentations resembling duck skin. Other ingredients in the dough may include water, soy bean, oil, sugar, salt.
The thin, pressed pieces of dough are then stewed in soy sauce and msg to give it flavour and colour, and sold canned.
In Vietnamese cooking, it is often served in dishes with a spicy brown sauce, sometimes in curries.
To use, drain from can. Unless otherwise directed by a recipe, fry the pieces in some oil until crispy and browned, then use in stir fries, etc. It is already seasoned a bit, but absorbs other flavours in a dish.
North American Mock Duck
The second version of Mock Duck is a North American recipe for stuff beef steak, which is very similar to German rouladen. It doesn’t actually look much like a duck.
You take a piece of flank or round steak, and flatten it out with a meat mallet, then roll it up around some breadcrumb stuffing, and secure the bundle with some string. The bundles are then baked covered in an oven with a bit of water around them to braise them. When the bundles are cooked, you make gray from the pan juices, and slice the bundles up to serve.
Some recipes omit the stuffing. Some recipes call for the bundles to be baked in a can of consomme or cream soup instead of just water. In the past, venison was sometimes used instead of beef.
Mock Duck was popular particularly in Pennsylvania Dutch cooking traditions, and served in some families around Christmas time.
Literature & Lore
“For the hostess who desires to serve something a little out of the ordinary for the Christmas dinner, Miss Hunt has a number of recipes that have been tested time and again in the Government ovens and have been found to be delicious and very tempting.
One of these relates to the preparation of “mock wild duck,” of which the ingredients are: One flank steak or one and a half pounds of round steak cut one-half inch thick, two lamb kidneys, one quarter cup of butter; one-half cup of cracker crumbs, a teaspoon of minced onion, salt, pepper and powdered thyme, sage and savory, two teaspoonfuls of flour, one tablespoonful sugar, three cupfuls stock or water.
To prepare the mock duck trim the kidneys of all fat, cords and veins. Cut into small pieces and spread evenly over one side of the steak, together with the crumbs, onions and seasonings. Roll and tie with a cord. Brown the roll in fat, them remove and make a gravy by heating the flour in the fat, adding the stock or water and sugar. Put the meat into the gravy and cook slowly until tender in a covered baking dish, a steamer, or a fireless cooker. Serve hot, with mashed potatoes and turnips.” — U.S. Expert Suggests Ideal Christmas Dinner: Miss Caroline L. Hunt, of Bureau of Home Economics of Department of Agriculture, Also Gives Reason Why She Has Selected Items on Her Menu. New York Times. 19 December 1915.
Mock Duck was also the name of a Chinese gang leader in New York’s Chinatown in the first years of the 1900s.