Heat half the oil in a frying pan, add the pork, season and fry for 5 minutes, breaking up the clumps, until browned. Remove from the pan and set aside.
Add the remaining oil and onion to the pan and cook for 5 minutes until softened, then add the garlic and cook for 30 seconds. Add the tomatoes, tomato purée and paprika and cook for a further 5 minutes until pulpy. Return the pork to the pan with the pepper, stir through and continue to cook for 10–12 minutes, then leave to cool.
Roll out the pastry on a lightly floured work surface until about 5 mm (¼ inch) thick. Using a small plate, cut out 8 x 15 cm (6 inch) circles, rerolling the trimmings as necessary. Spoon a little of the pork mixture on to one half of each circle. Brush around the edges with the egg yolk. Fold over the pastry, press out any air and then seal the edges with a fork. Brush with more egg.
Place the pastries on a large baking sheet and bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 15 minutes or until golden and crisp.