Clean the leeks cut into fine julienne and Fry in preheated butter. Place chopped tomatoes and fry well. Add peeled and sliced ​​potatoes, 2 pinches sugar, salt and 900 ml water and vazvaryava. Soup boil on low heat until tender potatoes, then compressed or beat with a mixer. The soup is warmed, add cream and immediately before presentation sprinkled with chopped parsley.