Combine 160g flour, 1/2 teaspoon dry yeast, 2/3 teaspoon sugar, 1/3 teaspoon salt, 2 tablespoons vegetable oil, and 125ml milk. Knead until the dough comes together.
Transfer the dough to a work surface and knead for 5-8 minutes, gradually adding the remaining 50-60g flour, until smooth. The dough should be slightly softer than dumpling dough.
Let the dough rest for 15 minutes.
Meanwhile, peel 200g potatoes, cut into chunks, and boil in salted water for 8-10 minutes until tender. Drain completely and mash into a smooth puree.
Finely chop 1 onion and fry in 2 tablespoons vegetable oil over medium heat for 3-4 minutes until light brown.
Add 250g minced meat to the onion, breaking it up with a spoon. Fry for 5-7 minutes over medium heat, stirring occasionally, until the moisture has evaporated. Season with salt and pepper to taste.
Fry 1/2 tablespoon flour in a dry pan over medium heat for 1 minute.
Add 15g butter and 1 tablespoon vegetable oil, mixing well with a whisk until smooth and lump-free.
Gradually pour in 120ml milk or cream while whisking continuously. Continue stirring over medium heat for 3-4 minutes until thickened.
Season with 1/3 teaspoon salt, 1/4 teaspoon black pepper, and 1/3 teaspoon nutmeg.
Pour the sauce over the meat mixture and let cool to room temperature.
Finely chop 1 bunch of parsley and stir into the cooled meat and sauce mixture.
Divide the dough into 4 equal portions and shape each into a ball.
Divide the cooled potato puree into 4 equal portions and shape each into a ball.
Mix 1 tablespoon flour with 2 tablespoons starch and dust your work surface with the mixture.
Grease the center of a dough ball with melted butter, place it butter-side down on the floured surface, and stretch it into a thin, flat circle roughly 20-25cm in diameter.
Place a potato ball in the center of the dough circle, flatten it slightly, and top with a portion of the meat and sauce mixture.
Gather the edges of the dough up and over the filling, twisting them at the top.
Fold down the dough edges that extend above the filling and smooth out the folds. Pinch off any excess dough and transfer the samsa to a parchment-lined baking sheet.
Repeat steps 16-19 with the remaining dough balls, potato balls, and meat portions.
Brush the top of each samsa with melted butter.
Bake in a preheated oven at 180°C (356°F) on the middle rack for 20-25 minutes until the top is golden brown.
Brush the finished samsa with additional melted butter and serve.