Mix flour, approx. 1 teaspoon salt, vinegar and oil first with the dough hooks of the hand mixer and then with your hands quickly to
knead into a smooth dough. Cover the dough and let it rest in a warm place for about 20 minutes
Chop olives. Clean and wash spring onion and cut into fine rings. Drain tuna thoroughly and tear with a fork. Grate cheese finely. Mix tuna, olives, spring onion and cheese. Season with salt and pepper
Roll out the dough on a lightly floured work surface until it is about 3-4 mm thin. Cut out approx. 20 circles (approx. 6 cm Ø). Place approx. 1 tsp. tuna mixture in the middle of each circle. Fold the dough plates and press them together at the edges with a fork
Place the dumplings on a baking tray lined with baking paper. Whisk egg yolk and milk. Brush the surface of the dough with it. Place in a preheated oven (electric cooker:
200 °C/air circulation: 175 °C/gas: level 3) Bake for 12-15 minutes. Serve the dumplings warm or cold