Fill a highball glass with ice.
Add 45ml coconut liqueur and 75ml fresh grapefruit juice directly into the glass.
Stir briefly to combine.
Top with 120ml soda water and give one gentle stir to integrate.
Garnish with a large grapefruit slice tucked against the inside of the glass.
Bumping the coconut liqueur from 30ml to 45ml brings better balance against the generous 75ml of grapefruit juice - at 30ml the drink skews too tart and the coconut character gets lost. A salted rim is an optional but worthwhile nod to the classic Paloma.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Lazy Coconut Paloma.