For the tarte tatin
Melt the butter and add the Quely María biscuit crumbs to make a pastry like mixture; spread this out evenly in the flan mould.
Cut the peaches into enough small rectangular pieces of the same size to cover the pastry base of the tarte tatin and arrange them in a layer on it.
Next slice the strawberries finely and lay the slices on top of the peach rectangles.
For the yoghurt sauce
Dissolve the sugar in the yoghurt and mix in the lemon zest. Set aside.
Assembly of the dessert
Put some of the yoghurt sauce on a plate.
Place a piece of the tarte tatin on top of the sauce and decorate with lemon zest, walnut pieces and peppermint leaves.