Mix orange or grapefruit juice with chilled soda water and plenty of ice. Add syrup to taste and pour just before serving.
Start with the fruit
Taste the orange or grapefruit juice before mixing. Some fruit is sweet enough on its own; another batch may need a little syrup. Fresh juice gives the drink character, but a good bottled juice can work when that is what you have.
Cut one thin slice for each glass. Save the remaining fruit for juice. A modest garnish leaves room for ice and makes the drink easier to sip.
Keep everything cold
Fill a glass with ice and pour in juice to about a third of the way up. Top with chilled soda, stir gently and taste. Add more juice if you want a stronger citrus flavour, or more soda for a lighter drink.
If you want sweetness, dissolve sugar in a little warm water first and let the syrup cool. Add it by the teaspoon. Sugar scattered straight into a cold glass tends to settle at the bottom.
Mix as people arrive
Prepare the juice and glasses ahead, but wait to add soda until you are ready to serve. That keeps the bubbles lively and makes each glass easy to adjust.
For a long lunch, put the juice and syrup on the table and keep the soda chilled nearby. Refill individual glasses as needed instead of making a large jug that loses its fizz.
