Put the quark in a bowl. Separate egg. Add egg yolk and milk and stir until smooth. Wash the lemon, dab dry, grate the peel thinly and squeeze the juice. Stir lemon peel and approx. 2 tablespoons of lemon juice into the quark mixture. Season to taste with sugar.
Beat the egg white until stiff. Fold the beaten egg whites into the quark mixture. Pour lemon curd into a glass bowl. Spread plum puree with a teaspoon on the quark. Decorate as you like with lemon wedges and lemon balm