For this recipe you need prune plums, which should be hard, small (not much larger than the size of a walnut) and ripe (the colour shoud be purple-blue). Here is a picture of what I used for this recipe.
1 lb prune plums (500g) 12-15 pieces
1 1/2 lb potatoes (700 g)
10 oz (250 g) all purpose flour (plus extra flour to coat the work surface when making the dumplings)
4 Tbs. vegetable oil
4 oz (100 g) butter
6 oz (150 g) plain breadcrumbs
6 oz sugar (150 g)
Vanilla sugar or vanilla essence
Wash and boil the potatoes for 25-30 minutes. The best potatoes are red ones, but any that are sticky rather than fluffy after boiling will work. Drain them and allow them to cool. After that, peel and mash them, adding salt. Then add the vegetable oil. Beat the 2 eggs, then add them to the potatoes as well. Next add the 10 oz of flour. Stir the mixture until all ingredients are incorporated. The dough should be sticky, as it is in the picture below.
In the meantime, wash and dry the plums. Then open them by squeezing the ends together in order to remove the pits. If you cannot remove the pits in this way, cutting them part way is also an acceptable method of removing the pits from the plums. But ideally the two halves of the plum should not be separated from one another.
With a spoon, take a portion of the dough and place it on a floured surface. Flatten it into a circle as you see in the photo below.
Place a plum in the center of the dough circle and then pull up the dough around it to cover it.
Do likewise with all the plums.
It takes skill and practice to finish the dough and the plums at the same time! The first time you try the recipe, there is a good chance that you will have plums or dough left over.
While you are making the dumplings, put a large (6-8 quart) pot of water to boil. Once the dumplings are prepared, and the water is boiling, place a batch of dumplings in the water. Gently keep them moving with a slotted spoon to ensure that they do not stick to the bottom. Boil for 15 minutes at medium-high temperature.
After they have been boiled, they need to be rolled in a mixture of breadcrumbs and sugar. And so either before you start making the dumplings, or while you are waiting for the dumplings to boil, melt the butter in a pan on low heat, and add to it the breadcrumbs, sugar, and vanilla. These ingredients are just being toasted lightly, so be careful not to burn them! When the dumplings are ready, place one or two at a time in the breadcrumb mixture and roll them through it. Continue until all the dumplings have been coated. Don't worry if you have breadcrumb mixture left over - it is good to spoon more of the mixture over dumplings when you eat them.
Serve them warm. We just had them basically as dinner and dessert all rolled into one!