Potatoes peel, wash and, up to 2 pieces, roughly chop. Wash the cucumber and cut it up to a small piece. Peel onion and chop finely. Heat oil in a pot.
Fry the potatoes, diced onions and cucumber in it. Deglaze with vegetable stock and 1/4 litre water and boil for 20 minutes. Finely dice remaining potatoes and cook in a little salted water for 10 minutes.
Finely dice the remaining cucumber. Cut the smoked ham into fine strips. Drain broth. Put potatoes in a blender, mash finely and place in a bowl. Add stock again and mix well.
Stir in the crème fraiche. Season to taste with salt and pepper. Add potato and cucumber cubes to the soup. Wash the borage, chop finely and add to the soup. Chill the soup. Serve the soup with strips of smoked salmon ham.
Garnish with borage.