Put the chicken breasts between two sheets of cling film and beat with a rolling pin until 1cm thick. Stir together the yogurt, lemon and thyme and season with pepper.
Put the chicken and marinade in a bowl and leave for 15 mins.
Meanwhile, put the mooli, cucumber, onions, bean sprouts and cress in a large salad bowl and toss.
Add the avocado, vinegar, oil, coriander and yogurt to a blender and blitz until smooth. Cook the chicken on a BBQ, in a chargrill pan or under the grill for approx. 8 mins, turning once.
Drizzle the dressing over the salad, scatter over the sesame seeds, add the sliced chicken on top and serve.