Halve the pink grapefruit and squeeze them thoroughly with a citrus press.
Pour the juice through a fine sieve into a jug to remove the pips and coarse fibres.
Rub the rosemary briefly between your palms to release its aroma.
Put the rosemary into the pink grapefruit juice and leave it to infuse briefly, until the juice smells lightly herbal.
If you like it a little milder, stir in the honey, then take the rosemary out again.
Serve ice-cold, with ice cubes or straight from the fridge.
Good to know
A juice like this tastes bright, tart and pleasantly grown-up. The rosemary gives it a delicate, fragrant depth without taking over.
Swaps
Pink grapefruit → blood orange (milder, also provides vitamin C) | honey → date paste (unrefined sweetness, plus a little fibre) | rosemary → fresh mint (fresher flavour, milder for children) | pink grapefruit → pomelo (often gentler, a little less bitter)
Allergens
Naturally gluten-free. Grapefruit can interact with certain medicines, honey isn't suitable for babies under 12 months, and in pregnancy the recipe is fine in normal amounts.