Step 1

Peel the potatoes, chop them into evenly-sized chunks and cook until fork-tender, about 15-20 minutes.

Step 2

While the potatoes are still warm, press them through a potato ricer or mash them with a potato masher. Let the potatoes cool before adding the other ingredients (warm potatoes will absorb more flour making your dumplings tough).

Step 3

Add flour, egg, and salt to the potatoes. Stir the ingredients with a spoon until roughly combined, then knead the dough with your hands until you have a ball of dough. Don't overwork the dough.

Step 4

Transfer the dough to a wooden board sprinkled with flour. The dough will be a little bit sticky but try to not add more flour or the dough may end up too tough.

Step 5

Divide the dough into 8 parts (if you have medium-sized plums).

Step 6

Cut all the plums almost in half but not all the way through, just enough to remove the stone. Place 1 sugar cube and a pinch of cinnamon in the place of the stone. Press both sides of the plum together.

Step 7

Flour your hands. Take one part of the dough and flatten it into a disk. Place one plum in the middle. Wrap the dough around the plum. Pinch the seam well so it won't open while cooking. Roll between your palms so you have a ball of dough.

Step 8

Place all the dumplings on a well-floured board.

Step 9

Cook knedle: Bring a large pot of salted water to a boil. Reduce the heat to a gentle simmer (the water should not boil rapidly!). Gently lower 4 knedle on a spoon into the water. After a minute or so, stir the dumplings gently with a wooden spoon to make sure they're not sticking to the bottom of the pot. When they float to the surface, cook them for 4 minutes. The cooking time may depend on the size of the dumplings. If you're not sure how long to cook them, you can test cook just 1 dumpling. Remove the cooked dumplings from the water with a slotted spoon and transfer to a plate. Drizzle with melted butter to prevent the dumplings from sticking to each other. Repeat with the remaining dumplings.

Step 10

While the dumplings are cooking, prepare the sides. Whisk the sour cream with powdered sugar until combined. Buttered breadcrumbs (bułka tarta): melt the butter in a medium pot/pan, when melted add the breadcrumbs, cook for a couple of minutes or until golden brown in color (be careful not to burn them).

Step 11

Serve your knedle with breadcrumb topping and sour cream and sprinkle them with cinnamon.

Step 12

Enjoy!