Coriander and lime dressing
1.Combine coconut milk, coriander root and stem mixture, garlic and lime leaves in a large saucepan. Bring to the boil. Add chicken and return to the boil. Reduce heat; simmer, uncovered, about 10 minutes or until chicken is cooked through. Remove from heat and stand chicken in poaching liquid for 10 minutes. Remove chicken from pan. When cool enough to handle, shred chicken coarsely.
2.Reserve 1 cup poaching liquid and discard remainder or keep for later use. Bring reserved liquid to the boil in same pan. Boil uncovered for about 10 minutes or until reduced by two-thirds. Add chicken to pan with liquid; cool 10 minutes.
3.To make coriander and lime dressing, use a mortar and pestle to crush coriander root and stem mixture, garlic, chillies and sugar until combined. Gradually add juice and crush until sugar dissolves. Stir in sauce.
4.In a small heatproof bowl, soak lemongrass with boiling water for about 4 minutes or until just tender; drain. Slice thinly and combine in a large bowl with cucumber, sprouts, mint, coriander leaves, chilli and dressing. Divide chicken mixture among serving plates; top with salad.