Peel the grapefruit so that the white skin is completely removed. Cut the fruits into 8 slices, sprinkle the slices with tequilla and let them steep for a short time. Mix crème fraîche, cinnamon and sieved icing sugar.
Cut the grapefruit slices to the middle and turn them into spirals. Arrange 2 red and 2 light spirals alternately on plates. Spread the sauce on the plates and serve sprinkled with chopped pistachios.