Rub the lemon peel, squeeze out the juice. Mix the buttermilk with lemon juice, lemon zest, sour cream and powdered sugar. Whip the cream until stiff and fold it into the buttermilk.
Put in the ice cream maker for approx. 35 minutes.
Without an ice cream machine, you fill the mixture into a bowl with a lid and place it in the freezer. Let freeze for approx. 4 hours. Stir vigorously every 30 minutes so that no ice crystals form.