Wash the lime in hot water, rub the peel thinly. Halve the fruit and squeeze it. Mix lime zest, sugar and salt. Distribute on a plate. Wash grapefruit hot, cut in half, cut off 4 slices and squeeze the rest.
Coat the edges of the glass with some grapefruit juice and press lightly into the lime salt. Fill glasses with ice. Distribute mescal and fruit juices one after the other in the glasses (approx. 400 ml each). Fill up with mineral water and decorate with grapefruit.