A shrub is sweet, sour and fruity in one jar

A shrub (also called a drinking vinegar) is fruit, sugar and vinegar left together until they become a syrup that tastes like fruit with a sharp edge. Add a splash to sparkling water and you get a grown-up soft drink with no alcohol, no special equipment and a fridge-shelf life of weeks. It is also a very old idea: sugar and acid are the two things that make a cocktail taste balanced, and a shrub puts both in one bottle.

The classic cold-process rule is easy to remember: equal weights of fruit, sugar and vinegar. Most home recipes use 1:1:1, then tell you to adjust to taste. The tool below does the sums for any amount of fruit, lets you bend the ratio, and tells you how many glasses a batch makes.

How to make one

This is the cold method, which many writers prefer because it gives a mellower, fresher-tasting syrup than heating.

1. Macerate. Chop the fruit, fold it with the sugar in a bowl, cover and refrigerate for one to two days. The sugar pulls the juice out of the fruit and dissolves into it.
2. Strain. Press the fruit gently through a sieve. Keep the syrup; the leftover fruit is good on yoghurt.
3. Add the vinegar. Stir it into the syrup, bottle it and leave it in the fridge for at least a day so the flavours settle together.
4. Serve. Pour 20 to 40 ml over ice and top up with sparkling water, to a total of about 200 ml. Adjust to taste.

Why it works

Sugar and fruit acid balance each other, the same way lemon juice and sugar do in a Daiquiri or a sour. Vinegar adds a cleaner, sharper acidity than citrus and brings its own savoury note, which is why a shrub tastes more like a drink for dinner than a squash. Vinegar is also acidic enough to help the syrup keep, though you should still store it in the fridge.

Sweet makes it easy to like; sour makes it hard to stop at one sip.

Choosing the vinegar matters. Apple cider vinegar is the traditional all-rounder. Some guides suggest white wine vinegar for delicate fruit and red wine vinegar for berries. Use a vinegar with about 5% acidity, and avoid anything very harsh or very dark and heavy (such as balsamic) until you know how the flavour behaves.

Variations and serving

Strawberry with black pepper, peach with white wine vinegar, plum with a cinnamon stick, or blackberry with sage all follow the same ratio. Try a shrub with still water, with tonic water, or with ginger beer for a longer drink. The same syrup can also go into a cocktail in place of sugar and citrus, but it is excellent with nothing stronger than bubbles in it.

Keep batches small. Cold-process shrubs should live in the fridge, and while some sources say vinegar preserves them for months, others only test refrigerated storage, so treat a few weeks as a safe window and throw it out if it grows mould or smells off.

What to look for

• Ripe, flavourful fruit. A shrub concentrates what the fruit already tastes like, so tired fruit makes a tired shrub.
• A clean jar or bottle with a tight lid. Wash it well and keep it cold.
• A fine sieve. It keeps the syrup clear and smooth.
• Taste as you go. The ratio is a start, not a law; fruit varies in sweetness and acidity from week to week.

If you are serving guests, say what is in it, keep a pitcher of plain water out too, and remember that an alcohol-free drink is a perfectly good choice on its own.