Mix the yogurt with the cream and sugar until all of the sugar has dissolved. Squeeze lemons and add the juice to the mixture.
Place the mixture in the freezer for approx. 5 minutes, then pour it into the ice cream maker and, depending on the type of ice cream maker, stir for approx. 30 minutes until it is firm.
Tastes wonderfully refreshingly sour for hot summer days and is quick to prepare.