Coconut Jelly — set in the shell of a young coconut

i. Origin & history

Coconut palms grow throughout southern China's tropical edges — Hainan island above all — and across Southeast Asia, and wherever they grow, coconut water and coconut milk find their way into sweets. Combined with agar, the seaweed-based gelling agent long used in East and Southeast Asian cooking (see agar-agar jelly), they make some of the region's simplest and most refreshing desserts.

The coconut-in-shell version is particularly associated with Thailand, where wun maprao (วุ้นมะพร้าว, 'coconut jelly') is sold by street vendors and at markets, the jelly set right inside young green coconuts with their tops sliced off. In Hong Kong, Taiwan and southern China, yēzi dòng (椰子凍) appears in dessert shops and dim sum restaurants, sometimes as a clear coconut-water jelly in the shell, sometimes as a firm white coconut-milk jelly cut into squares. Hainan, famous for its coconuts, has its own coconut-jelly and coconut-milk sweets.

Over the past decade, coconut jelly in the shell has become a popular dessert well beyond Asia, helped by its photogenic look: a whole coconut, opened to show a translucent jelly with a layer of white, served with a spoon. Inside, the young coconut's soft flesh is scooped up along with the jelly.

A different, cornflour- or gelatin-set dessert, the Hong Kong coconut milk pudding (椰汁糕), is also often called coconut jelly in English; it is denser and creamier. The cousins of both include Malaysian and Indonesian layered kuih such as kue lapis, Thai khanom chan, and the Filipino buko pandan, which mixes young coconut and pandan jelly.

ii. Setting coconut water without losing its flavour

Fresh coconut water is delicate, faintly sweet and slightly nutty, and its flavour fades with heat. Agar is ideal for setting it because it needs only a brief boil to dissolve and sets quickly at room temperature, so the coconut water need not be cooked for long. The method is to dissolve the agar in a portion of the coconut water, boil it for two minutes, and then stir in the rest of the coconut water off the heat, keeping more of the fresh flavour.

Coconut water's sweetness varies from nut to nut, so taste it before adding sugar. A young coconut with sweet water may need only a spoonful; a bland one needs more, and a pinch of salt sharpens the flavour. The amount of agar decides the texture: about 4 g per 500 ml gives a jelly that holds its shape but is tender and slightly crisp, not rubbery.

The creamy layer is coconut milk set the same way. Because agar sets in minutes at room temperature, the layers have to be timed: pour the clear jelly first, wait until it has set but is still warm, then add the coconut-milk layer so the two fuse. If the first layer has cooled completely, the layers can separate when scooped.

Setting the jelly in the shell is practical as well as pretty. The coconut shell is its own mould and serving bowl, and the soft, slippery flesh lining it becomes part of every spoonful. Young green or trimmed white 'Thai' coconuts are used, because their flesh is soft and their water sweet; mature brown coconuts have hard flesh and much less water.

iii. Ingredients

Makes 4 servings · scroll the side panel to adjust

• 2 young Thai coconuts
• 500 ml coconut water (from the coconuts, topped up if needed)
• 4 g agar powder (clear layer)
• 30 g sugar, or to taste (clear layer)
• 200 ml coconut milk
• 50 ml water (white layer)
• 2 g agar powder (white layer)
• 25 g sugar (white layer)
• 1 pinch of salt
• 1 pandan leaf, knotted (optional)

Young Thai coconuts — the white, pointed, trimmed kind, or green ones — are sold in Asian supermarkets. If you cannot get them, use 500 ml good-quality pure coconut water and set the jelly in small glasses or a tin, adding some sliced fresh young coconut flesh (sold frozen). Agar powder is essential; gelatin gives a softer jelly that melts at room temperature. Full-fat coconut milk gives a rich white layer. Pandan adds a vanilla-like fragrance.

iv. Method

1. Open the coconuts: with a heavy knife or cleaver, tap firmly in a circle round the pointed top of each coconut to crack the shell, then prise off a lid about 6–7 cm across. Pour the water into a jug through a sieve. Rinse out any shell fragments and stand the coconuts upright in cups or a muffin tin.
2. Measure the coconut water and top up to 500 ml with bottled coconut water if needed. Taste it.
3. Whisk the 4 g agar into 150 ml of the coconut water in a small pan. Bring to the boil with the pandan leaf, stirring, and simmer for 2 minutes until the agar has fully dissolved. Stir in the sugar to taste.
4. Off the heat, remove the pandan and stir in the remaining 350 ml coconut water. Pour into the coconuts to fill them about three-quarters full. Leave for 15–20 minutes, until set on top but still warm.
5. Meanwhile, whisk the 2 g agar into the 50 ml water, add the coconut milk, sugar and salt and bring to a simmer, stirring constantly, for 2 minutes.
6. Gently pour the coconut-milk mixture over the back of a spoon onto the clear jelly to fill the coconuts.
7. Leave at room temperature for 20 minutes, then chill for at least 2 hours.
8. Serve whole with spoons, scooping the jelly and soft flesh together, or cut each coconut into wedges with a heavy knife.

v. Tips & common mistakes

• Taste the coconut water first. Sweetness varies greatly; adjust the sugar to suit each batch.
• Boil the agar fully. Undissolved agar gives a weak, grainy set; two full minutes at the boil.
• Add most of the coconut water off the heat. It keeps the fresh flavour that boiling dulls.
• Pour the second layer onto a warm, set first layer. Too early and the layers mix; too late and they separate.
• Keep the coconuts upright. Stand them in cups or a muffin tin so the jelly sets level.
• Be careful opening coconuts. Use a heavy knife, tap rather than chop, and keep your hand well away.

vi. Variations

Clear coconut-water jelly skips the milk layer for a pure, translucent jelly. Hong Kong coconut milk pudding sets coconut milk and milk with gelatin into soft white squares. Pandan coconut jelly adds pandan juice to one layer for green-and-white stripes. Thai cooks sometimes add butterfly pea for a blue layer. Diced mango, lychee or longan can be set into the clear layer.

For layered agar jellies, see agar-agar jelly; for other coconut desserts, try buko pandan, taro cake and sago gula melaka.

vii. Serving & storage

Serve coconut jelly very cold, in the shell or cut into wedges, as a light dessert after a spicy or rich meal, at summer parties or as a refreshing afternoon snack. It needs no accompaniment.

Keep the coconuts covered with cling film in the fridge and eat within 2 days, as fresh coconut water and flesh spoil quickly. The jelly cannot be frozen; freezing destroys the agar gel.

ix. More from Chinese

• Agar-Agar Jelly — layered pandan and coconut
• Taro Cake — steamed taro and coconut cake
• Mung Bean Cake — pressed bean pastries
• Tangyuan — glutinous rice balls
• Buko Pandan — young coconut and pandan jelly
• Tub Tim Krob — Thai water chestnut rubies