Peel and discard the outer leaves of the lemongrass- they can sometimes be tough. Cut the inner leaves into short lengths and put in the food processor. Peel the ginger, then slice into thin pieces and add to the lemongrass. Chop the chillies, discarding their stems and add to the ginger with the peeled garlic. Roughly chop the stems and half of the leaves of the coriander to add to the food processor, reserving the rest for later.
Grate the lime zest into the food processor, reserving the limes for later, then turn the machine on and let it chop everything to a coarse paste. Add a little groundnut oil and scrape the sides down with a spatula if it sticks. Add the fish sauce, soy sauce and the tomatoes and process for a few seconds longer.
Warm a further tablespoon of groundnut oil in a deep pan over a moderate to high heat and use it to brown the chicken pieces, turning them so they colour nicely on both sides. Lift the chicken pieces out and pour away anything more than a tablespoon of oil and juices. Add the spice paste and let it fry over a moderate heat for two minutes till fragrant, stirring almost constantly, then return the chicken to the pan. Pour over the coconut milk, stir, cover and leave to simmer over a low heat for 15-20 minutes. Meanwhile halve and stone the apricots and leave them to one side.
Test the chicken for doneness making certain it’s cooked right the way through, then add the apricots. Leave to simmer for a few minutes, then add the juice of the limes and the reserved coriander leaves.