Peel the carrots, cut in half lengthways and cut into 1 cm pieces. Peel the potatoes and cut them into pieces of the same size. Cover and bring both to the boil in vegetable stock and simmer over medium heat for about 10 minutes. In the meantime, clean and wash the leek and cut into 1 cm thick rings. After 5 minutes add to the remaining vegetables and finish cooking. Season the soup with salt and pepper.
Fry the king prawns in a little butter and add to the soup just before serving. For decoration, stick a few prawns with a little dill on the edge of the plate or line them up on a skewer.