Peel the cucumber(s), halve lengthwise, deseed and slice.
Peel the onion and chop finely. Peel the potatoes and cut into small cubes.
In a heavy-based pan, melt the butter and fry the onion until translucent. Add the potato cubes and cucumber strips and sauté for 4-5 minutes, but do not brown.
Cut the smoked sausage into thin slices.
Add the stock, salt and pepper to the vegetables and cook gently for about 15 minutes.
In a pan, heat the oil and fry the slices of sausage on both sides until browned.
Rinse the dill, shake dry and finely chop.
Remove half of the vegetables from the saucepan and set aside. Add the cream to the soup, puree with a hand blender and season to taste. Add the reserved vegetables and warm briefly in the soup. Serve in bowls, top with fried sausage slices and sprinkle with dill.