Wash the lemon hot, dry and grate the peel thinly. Halve the fruit, squeeze 1 half. Wash the rosemary, shake dry. Caramelise 3 tbsp.
sugar in a pot, roast rosemary briefly in it. Add lemon juice and berries, bring to the boil and simmer for about 4 minutes. Remove rosemary. Let the berries cool down briefly.
In the meantime, whisk the sour cream and icing sugar with the whisks of the mixer for about 3 minutes. Stir in yoghurt. Layer berries and yoghurt cream alternately in four glasses and chill for at least 1 hour. Mix 1 tbsp. sugar and lemon peel and sprinkle the yoghurt with it before serving.