Dissolve the yeast and sugar in lukewarm water in a bowl. Add flour, salt, yogurt, and sunflower oil, and knead the dough until soft and smooth. Cover and let rise in a warm place for at least 45 minutes.
Meanwhile, prepare the spinach and chop it finely. Finely chop the onion and sauté it in a pan. Add the spinach to the onion and sauté. Season with salt, black pepper, and nutmeg to taste. Let the spinach cool slightly.
Crumble the cheese finely and mix it with the spinach and chopped tomato. Break 3 eggs into the mixture.
Divide the dough into 4-6 equal parts and roll out into elongated oval shapes. Place the spinach-cheese mixture in the center, fold the edges, and twist the ends.
Beat one egg and brush the visible spinach mixture. Finally, beat 1 yolk with milk, brush the edges with it, and sprinkle with black cumin.
Bake in a preheated oven at 200 °C (top/bottom heat) for at least 20 minutes.