Light-bound mustard soup with a lid of puff pastry

Beat the egg yolks with a little water. Mix the cornstarch with a little water. Heat the stock and stir the mustard through the hot stock with a whisk.

Preheat the oven to 200ºC. Melt the butter in a frying pan and fry the leek and the celery for a few minutes on a low heat. Stir the vegetables occasionally.

Add the vegetables to the stock. Now bind the soup by adding the corn mixture with stirring.

Spoon the soup into refractory bowls with a diameter no greater than 8 cm. Brush the edge of the bowls on the outside with egg yolk. Place the slices of puff pastry on the soup bowls and press the overhanging edge of the dough firmly against the smeared edges. Brush these lids of puff pastry carefully with a brush dipped in the egg yolks. A hole may not be made in the dough.

Sprinkle the dough with a little sesame seed. Put the bowls in the oven for about 20 minutes. Remove the bowls if the dumpling dough has a nice golden yellow color. Serve the soup immediately.