Wash oranges and limes, dry them and rub the peel, cut the fruit in half and squeeze. Bring the juice to a boil in a saucepan with the grated zest and cook covered over low heat for 10 minutes. Cut the mint into thin strips.
Mix the creme fraiche and quark. Stir in orange-lime juice and mint strips and season with salt and pepper.
Orange-lime dip goes well with fried salmon medallions, green and white asparagus tips and grilled prawns.