Place the puff pastry slices next to each other and let them thaw for about 10 minutes. Rinse and drain the corn and beans. Peel and finely dice the onion. Cut feta into cubes and mix with sour cream. Heat oil.
Fry onion and ground beef until finely crumbly. Season with salt and cayenne pepper. Add tomato paste. Stir in corn, beans and feta. Spread the minced meat mixture on the puff pastry slices and fold them into a bag. Place on 2 baking trays lined with baking paper. Whisk the egg yolk and spread it on the puff pastry. Grate the Gouda and sprinkle over the top. Bake in the preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: level 4) for 10-12 minutes.
Spread the minced meat mixture on the puff pastry slices and fold them into a bag. Place on 2 baking trays lined with baking paper. Whisk the egg yolk and spread it on the puff pastry. Grate the Gouda and sprinkle over the top. Bake in the preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: level 4) for 10-12 minutes. Serve sprinkled with small chive rolls