Heat the oil in a saucepan, add the onion and pumpkin and fry for 5 minutes until softened. Stir in the garlic and paprika, then the tomatoes and a little salt and pepper. Cover and simmer for 15 minutes, stirring from time to time until the pumpkin is just cooked.
Cut the pastry into 4 pieces then roll each piece out on a lightly floured surface until large enough to line a buttered 12 cm (5 inch) fluted loose-bottomed tart tin. Press over the base and sides, then trim the top level with the tin. Reserve the pastry trimmings.
Put the tarts on a baking sheet, spoon in the pumpkin filling, then sprinkle with crumbled feta. Brush the top edge of the pastry with a little beaten egg. Roll out the pastry trimmings and cut into narrow strips, long enough to go over the tops of the pies. Arrange as a lattice on each pie, then brush with a little egg.
Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 20–25 minutes until golden brown. Leave to stand for 5 minutes, then remove from the tins and serve warm or cold.