1. Rinse the leeks several times. Cut them into slices.
2. Melt the butter gently in a sauté pan.
3. Place the leeks in the pan. Add 4 tablespoons of water. Season with salt and pepper.
4. Cook over low heat for 7 to 8 minutes, stirring occasionally until there is no more liquid.
5. Preheat the oven to 425°F (210°C).
6. Dissolve the flour in the cream. Pour it over the leeks.
7. Add the roughly grated Edam cheese. Season with curry.
8. Adjust the seasoning with salt and pepper if necessary.
9. Mix well and let it cool.
10. Unroll the puff pastry on a work surface and, using a large overturned bowl, cut out 4 discs. Spread the leeks on them.
11. Fold the discs in half to form turnovers.
12. Lightly moisten the edges and press them together to seal.
13. Brush the surface of the turnovers with beaten egg yolk mixed with a tablespoon of water. Place them on a baking sheet.
14. Slide them into the oven and let them cook for about 15 minutes, until they are puffed and golden.
15. Serve hot. Accompanied by a seasonal salad.