Star fruit

Averrhoa carambola · carambola · kamrakh · kamrak

Slice it across and the star falls out ready-made — sourness with a shape.

What it is

Star fruit is a waxy, ridged tropical fruit, pale green to yellow, that cuts crossways into a perfect five-pointed star. The taste runs from sharply sour to mildly sweet depending on ripeness, with a clean, watery, faintly citrus juice. It is eaten fresh and, in the plains, pressed and sweetened into a tart cooling sharbat.

Where it comes from

The tree grows across the warm, humid parts of the subcontinent and Southeast Asia. In the Indus Plains and the wider north it is a familiar sour fruit, turned into pickles, chutneys and — the reason it earns a place here — a bright, astringent summer drink.

What it's called

Star fruit · carambola · kamrakh (Hindi) · kamrak (the Sindhi name and the drink, kamrak sharbat).

In the kitchen

For a sharbat the fruit is juiced or blended, strained, and sweetened with sugar and a little salt, sometimes a whisper of black pepper — a pale green-gold cooler. A thin star-cut slice on the rim shows the fruit off. The very sour varieties also go into chutneys and pickles. Choose firm, evenly yellow fruit; deep green ones are mouth-puckeringly tart.

What we know about the claims

One genuine caution belongs here: star fruit contains caramboxin and oxalates, and is dangerous to people with kidney disease, in whom it can cause serious neurological harm. For healthy kidneys it is a normal fruit. It is worth knowing, and worth a line on any recipe that uses it.

Choosing and buying

Fresh star fruit appears seasonally in UK and US South Asian, Caribbean and East Asian grocers, and larger supermarkets; pick fruit that is firm with just-browning rib edges. There is no good dried substitute — the drink wants the fresh juice.