1green chilliroughly chopped (seeds included), plus extra, sliced, to serve
Begin by making the paste. Using a vegetable peeler, pare a thick strip of lime zest, then remove as much of the pith from the strip as possible with a small sharp knife. Reserve the rest of the lime for serving.
Combine the lime zest and the rest of the paste ingredients in a food processor or blender and whizz to a super-fne paste. If the paste looks too chunky, add a splash of water and whizz again.
Open the tin of coconut milk and spoon the ‘cream’ from the top into a deep pan or wok with a lid, set over a low-medium heat. Add the paste and cook, stirring continuously, until the liquid is fragrant and bubbling.
Pour in the remaining coconut milk and the stock, then add the chicken. Bring to a simmer then cook for 40-45 minutes, until the chicken is tender. When the sauce has reduced to the consistency of single cream, cover for the remaining cooking time, stirring occasionally.
Remove the lid and stir in the fish sauce, palm sugar, green beans and chopped coriander leaves. Leave to simmer gently, uncovered, for 3-4 minutes, or until the beans are just cooked. Meanwhile, cut the reserved lime into wedges.
Season to taste with a little extra fsh sauce, palm sugar and lime juice. Just before serving, scatter over the extra coriander and a little more chilli, if you like it hot. Serve with jasmine rice and the remaining lime wedges on the side.
Thai food is all about finding a good balance between the four main flavours - hot, sweet, sour and salty - which is why it's crucial to taste before serving. Add extra chilli for heat, sugar for sweetness, fish sauce for more salt and fresh lime juice for a hint of sourness.
If using chicken on the bone, discard the skin and add the whole pieces to the sauce. Bones conduct heat, so the chicken might cook more quickly.
If you have kaffir lime leaves to hand, use three of these in place of the pared lime - they're a traditional ingredient in Thai cookery and have a similar flavour to lime zest.
Thai curries are traditionally much thinner than Indian curries, but if you prefer yours a little richer, stir in ½ x 160ml tin coconut cream just before serving.