For the ice cream, mix quark and 75 g sugar, gradually adding 75 g cream and 2 tablespoons milk. Wash lemon hot, grate dry and finely grate peel. Halve lemon and squeeze juice.
Stir lemon zest and juice into the quark mixture. Chill the ice cream mixture for about 10 minutes, then freeze in the ice cream machine. For the pistachio mousse, mix 200 g cream, 100 ml milk and pistachio cream and put it into an espresso bottle, screw it down and load it with gas cartridges.
Keep cold until use. (If you don't have an Espuma bottle, you can whip cream and 2-3 tbsp. pistachio cream with the whisks of the hand mixer, put it in a cool place. Milk in the cream must then be avoided). Peel the pineapple, cut out the hard stalk.
Cut the flesh into small pieces. Heat butter in a large pan, add pineapple, sprinkle with 3 tbsp. sugar and simmer until the sugar is completely dissolved. In the meantime wash tarragon, shake dry, pluck leaves from the stalks and chop.
Halve the orange and squeeze the juice. Add tarragon to the pineapple, deglaze with orange juice. Arrange pineapple and pistachio mousse on plates. Form ice cream into balls and arrange on plates. Possibly with sugar spirals and