Cut a long, spiral zest by running a knife around the grapefruit (like peeling an apple). Take care to slice off only the zest and not the fruit.
Trim the edges of the zest with your knife so that the zest is around 1 cm to 1.5 cm wide.
Place one end of the zest in the bottom of the glass and spiral the other end around the glass. Fill your cup to the brim with ice cubes to keep the zest in place.
Fold the protruding end of the zest over the edge of your glass, allowing it to dangle.
Pour the shot of espresso into the glass.
Top up the glass with equal parts coconut water and tonic water.
