Combine Dry Ingredients: In a large mixing bowl, sift together 750 grams of flour with 1.5 teaspoons of baking powder and 1 teaspoon of salt.

Add Butter: Incorporate 300 grams of butter into the flour mixture. Use your fingertips or a pastry cutter to blend until the mixture resembles coarse crumbs.

Mix Wet Ingredients: In a separate bowl, whisk together 2 whole eggs and 1 egg white with 200 grams of sour cream.

Combine Mixtures: Gradually add the egg and sour cream mixture to the flour and butter, stirring until a dough begins to form.

Knead the Dough: Turn the dough out onto a floured surface and knead gently until smooth. Wrap in cling film and refrigerate for at least 30 minutes.

Cook Potatoes and Onions: Peel and dice 3 potatoes and 4 onions. In a pan over medium heat, cook the onions until they're translucent. Add the diced potatoes and cook until just tender.

Prepare Meat: In another pan, cook 400 grams of minced meat until browned. Season with salt, pepper, cumin (zira), and coriander to taste.

Combine Filling: Mix the cooked meat, potatoes, and onions together. Adjust seasoning as needed.

Preheat Oven: Heat your oven to 200°C (392°F).

Roll Out Dough: Remove the dough from the refrigerator. On a floured surface, roll out the dough to about 1/4 inch thickness.

Cut Out Circles: Use a round cutter or a cup to cut out circles from the dough.

Add Filling: Spoon some of the filling onto one half of each dough circle. Be careful not to overfill.

Seal Pies: Fold the dough over the filling to create a half-moon shape. Seal the edges by crimping with a fork.

Prepare for Baking: Beat the reserved egg yolk and brush over the top of each pie for a golden finish.

Bake: Place pies on a baking sheet lined with parchment paper. Bake for about 20-25 minutes, or until golden and crisp.