For the filling: Saute onions with oil in a pan until softened and brown.
Grate warm potato into a bowl and add the sauteed onion, salt and pepper. Mix together to evenly distribute ingredients into a mash-like mixture.
For the dough: Line a baking sheet with parchment paper and set aside.
Add flour and salt to the cleaned bowl of a stand mixer and slowly mix. Add water and oil. Mix completely. Remove dough and work into a roll, then a log shape.
Slice a thin piece of dough and roll into a thin 4-inch round. Place 1 tablespoon potato mixture in the center of the dough circle, then fold circle into a half-moon and seal the edges. Place on the lined baking sheet. Fold over the edge of the dumpling, like a pot sticker. Repeat with remaining dough and filling. Refrigerate for about 10 minutes to hold their shape.
Bring a large pot of salted water to a boil. Add dumplings; they will rise to the top once they are finished cooking.
For the garnish: Caramelize onions in some oil in a frying pan until golden brown and crispy, 5 minutes. Plate dumplings and lay caramelized onions on top with salt, pepper and sour cream.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.