• Cut the pumpkin into approx. 2mm thin slices and fry on both sides in a hot grill pan, seasoning lightly with salt. Then put aside on a plate.
• Put the yoghurt in a bowl with the mustard, a little grated tonka bean, salt and pepper and mix well. Mash the ready-to-eat chestnuts well and fold into the sauce.
• Cut the leek into approx. 2mm fine rings, place in a bowl and set aside.
• Add salt and pepper to the mince in a bowl and mix well. It is easiest to form equal-sized patties with a burger ring but you can do by hand.
• Preheat the oven to 150°C. Sear the patties briefly on both sides in a very hot grill pan and then place them on a baking tray. Bake in oven until cooked.
• Sprinkle water over the centre of the pita breads and bake in the oven at 220°C for a few minutes.
• To assemble: put the sauce on each bun, followed by the pumpkin, patty, feta and leek. Finally, drizzle with pumpkin seed oil and sprinkle with the petals.

Photo gallery of the preparation