Peel all of the potatoes and boil one-third of them until tender.
Run the raw potato through the meat grinder, then strain it through a strainer and squeeze to remove excess water.
Pour the water out of the bowl, wipe it down, and put the ground potato back in. Pass the boiled potatoes through the grinder into the same bowl and stir them together with a fork.
Add the egg and stir vigorously. If the potatoes are very wet, only use the yolk.
Add salt and pepper to taste. (Remember, they will be served with a bacon sour cream sauce, so consider how salty your bacon is.)
Sprinkle the starch in tablespoons over the potatoes and continue blending with the fork. You could use the mixer's dough attachment for this, but I prefer to do it by hand so I can feel when it reaches the proper consistency for forming. When the dough is no longer sloppy, you are ready to form the dumplings.
Take a palmful of dough in one hand and flatten it slightly to form a shallow bowl in the centre (see video). Add about a teaspoon of cottage cheese to the bowl and form the covering piece in the other hand. Place the cover over and gently press the sides in making sure no cottage cheese is visible. Press it together like a snowball and place it on a smooth plate or pan. Continue until all the dough is used.
Bring a large pot or pan of salted water to a boil. It should be just deep enough to cover the dumplings. Gently place the dumplings in the water and return to a simmer. Simmer for 20 minutes, rolling them occasionally if they aren’t completely submerged.
While the dumplings are cooking, fry the bacon in a pot until just crisp, then drain the fat. Off the heat, add the sour cream and stir it in. The pot should be just warm, not hot, or the sour cream will separate. Keep the burner on low and the sauce warm until the dumplings are ready.
Remove the dumplings from the water, transfer them to a bowl, and place them in a warm oven or serve immediately. Ladle generous portions of the sauce and enjoy!
