Preheat the oven to 220 degrees Celsius.

Finely chop the red bell pepper and onion.

In a mixing bowl, combine the ground beef with chosen spices, then add 2 to 3 tablespoons of ketchup, chopped bell pepper, onion, and the beaten egg. Mix until well blended.

Roll out the puff pastry on a floured surface to about half a centimeter thick.

Spread the beef mixture on the pastry, leaving a 2 to 3 cm border.

Sprinkle grated mozzarella on top.

Brush the edges with beaten egg, roll up the pastry, and pinch the edges to seal.

Place on a baking sheet lined with parchment paper, piercing holes in the top.

Brush the tops with egg yolk.

Bake at 220 degrees Celsius for 10 minutes, then reduce the temperature to 180 degrees Celsius and bake for another 25 minutes until golden brown.

Allow to cool slightly before serving with ketchup or your favorite dipping sauce.