Defrost the blueberries. Meanwhile cut the vanilla pod lengthwise and scrape out the pulp. Mix quark, vanilla pulp and 3 tbsp. sugar. Whip cream until stiff and fold in. Divide the cream into four small bowls.
Drain blueberries well, collect the juice. Heat butter in a pan. Sauté the berries for 2-3 minutes. Sprinkle with 1 tbsp. sugar and caramelise slightly. Deglaze with vinegar and blueberry juice, bring to the boil and simmer for 1 minute.
Allow to cool a little, then apply to the curd cream.