Rinse the meat and egg with water and pat dry with a paper towel. Pass the minced meat through a meat grinder or chop finely. Peel the onion, wash and finely chop. To serve, wash the parsley, pat dry on paper towels and finely chop. Prepare a baking sheet, parchment paper, and cling film.
Prepare the dough. Pour kefir into a deep bowl, heat slightly, dissolve the yeast, add sugar, salt and egg. Stir, add flour and knead into a thick dough. Let the dough rise for 10-15 minutes. Divide into 2 parts, roll each into a thin rectangle. Brush the first rectangle with butter. Place the second rectangle on it, grease the top with butter. Roll both layers together into a tight tube, cut into two parts, wrap in cling film and refrigerate for 2 hours.
Prepare the filling. Combine the onion with minced meat, add salt, pepper and cumin. Mix thoroughly.
Prepare samsa. Take out the dough, cut into squares, roll out a little and place the filling in the center of each piece. Give the baked goods a triangular shape. Let stand for 15 minutes on the counter. Preheat the oven to 180 degrees. Line a baking sheet with parchment. Brush the samsa with yolk and place on a baking sheet. Sprinkle with sesame seeds. Bake for 40 minutes.
Serve hot samsa with meat with parsley.