Heat the clarified butter in a frying pan, brown the meat for approx. 1 min. on each side, remove from the pan, season with salt and leave to cool.
Heat the clarified butter in the same frying pan. Briefly sauté the leek, season. Pour in the water, simmer for approx. 10 mins. Pour in the sour single cream, simmer for approx. 5 mins. until just soft. Cover the leeks and keep warm.
Mix the mint and thyme, sprinkle half onto the work surface with a little flour, place 300 g of puff pastry on top. Sprinkle with the remainder of the herbs. Roll out the puff pastry into a rectangle of approx. 25 x 60 cm, cut crosswise into 4 strips. Sprinkle the almonds in the middle of one half of the pastry, place the meat on top. Add the slices of apple. Brush the pastry edges with egg, fold loosely over the meat, press the edges down firmly, transfer to a baking tray lined with baking paper. Brush the parcels with egg. Roll out the remaining pastry thinly, cut out stars, arrange on top of the parcels, brush with egg.
Approx. 20 mins. in the lower half of an oven preheated to 220°C. Heat the creamed leeks, serve with the meat.