Mix 500 g flour, 1⁄2 TL salt, 1 TL sugar and baking powder in a bowl. Add butter, 2 eggs and 200 g sour cream. Knead everything to a soft but not sticky dough, add some flour if necessary.
Wrap in foil and chill for about 30 minutes. Line three baking trays with baking paper (or use one tray several times).
For the filling, peel and finely dice the onion. Heat the oil in a pan. Fry the minced meat until crumbly. Fry the onion briefly. Season well with salt and pepper. Remove from heat, season again and let cool down a little.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Open the dough in portions.
of a floured work surface, roll out to a thickness of approx. 5 mm. Cut out circles of approx. 8 cm Ø. Knead the rest together again, roll out again and cut out until the dough is used up. Place 1 heaped teaspoon of filling in the middle of each circle of dough.
Press the edges together.
Distribute the pirogi with the seam facing down on the sheets. Whisk 1 egg, brush the dough with it. Bake in a hot oven for 15-20 minutes, one sheet at a time.
In the meantime, finely dice the cucumbers for the dip. Wash the dill, shake dry and chop finely. Stir 300 g sour cream with the stock until smooth. Season with salt, pepper and 1 pinch of sugar. Stir in cucumbers and dill.
Take pirogi out of the oven, arrange with dip and remaining mince.