Elephant apple

What it is

Elephant apple, Dillenia indica, measures about 8–10 cm (3–4 in) across. Its rounded shape comes from thick, overlapping sepals: the green parts that once enclosed the flower. These swell around the true fruit as it develops. The layers have a firm texture and enough acidity to season a savoury dish.

Where it comes from

The tree is native to India, Sri Lanka and southern China, across mainland Southeast Asia to Sumatra, Java and Borneo. Its rippled leaves and large, fragrant white flowers also make it a garden tree through the tropics and subtropics. In Assam the fruit is called ou tenga; in Bengal it is chalta.

How it's eaten where it grows

In Assam, ou tenga dal cooks elephant apple with pink lentils and turmeric. A mustard-oil seasoning brings garlic, fenugreek, mustard seeds and green chilli to the pot. The fruit also goes into fish curries and pickles.

Bengali chaltar chutney can pair the fruit with jolpai, Indian olives. One autumn version of this sweet-and-sour chutney adds fragrant rice for flavour and grated coconut for texture. In Thailand, sliced young elephant apples go into kaeng som, a sweet-and-sour soup, and kaeng ma tad, a spicy elephant-apple soup.

How it's grown

Elephant apple grows beside forest streams and rivers and can become a tree 30 m (98 ft) tall. New plants can start from seed or from air layering, which makes a branch grow roots while it is still attached to the parent tree.

When and where you'll find it

In Bengal, unripe chalta usually reaches markets from early October, ready for chutney. Over the following months it gets sweeter and more fibrous and goes into pickles. Preserved fruit also reaches specialist Bengali food shops: The Bengal Store in Kolkata lists a homemade chalta pickle online.