Put the chicken between two sheets of cling film and bash it flat with a rolling pin or heavy pan. Make sure it is all equal thickness.
Put the coconut milk, palm sugar and fishsauce in a wide shallow pan. Add the chicken to the cold liquid. Gently bring to a simmer. Cook for 15 minutes, take off the heat and leave to cool in the liquid.
Using a vegetable peeler, cut the cucumber into long thin ribbons
Take the chicken from the poaching liquid and slice as thinly as possible, them mix all the ingredients except the roasted peanuts. Serve drizzled with some of the poaching liquid and sprinkle with the peanuts
Notes
Be sure to taste your chillies before you add them to your salad. We used it in liberal amounts as our red chillies are usually rather mild. Not this time! It was blazing hot! So we should've checked but forgot...