Lemongrass and pandan cooler (Nam takrai)

1. Wash the lemongrass, bruise the stalks with a rolling pin or the back of a knife and cut into 5 cm pieces; tie the pandan leaves in a knot.

2. Bring the water to the boil with the lemongrass and pandan, then simmer for 15 minutes until the water is pale green and fragrant.

3. Stir in the sugar until dissolved, then take off the heat and leave to cool.

4. Strain and chill thoroughly in the fridge.

5. Just before serving, squeeze in the lime juice and add more sugar to taste.

6. Pour into glasses filled with ice cubes and garnish with a lemongrass stalk or lime slice.

Tip: In Thailand it is loved both as a cooler and as a digestive drink. It's lovely hot as a tea too; together, pandan and lemongrass give a vanilla-citrus aroma.