Wash the potatoes, wrap in aluminium foil and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 1 1/2 hours. In the meantime mix sour cream with 1 teaspoon chilli powder.
Cut the cress from the bed and, except for something to garnish, cut it smaller. Remove the potatoes, wrap them from the foil, cut them lengthwise in the middle up to 1 cm before the edge and press them apart.
Alternately fold the strawberry puree and cream into the beaten egg white, do not stir. Pour the strawberry puree into a bowl and decorate with a halved strawberry.