Mix the yogurt and curry powder together in a glass or plastic bowl and add the first T of chopped coriander.
Place the chicken breasts between sheets of cling film, then use a meat mallet or rolling pin to beat them out until slightly flattened. Add them to the yogurt mixture, stirring to coat. Cover, chill and leave to marinate for at least 30 minutes or overnight.
Cook the rice with the stock cube until tender. Drain and rinse with cold water to cool quickly. add the carrot, red pepper, chilli, mint and remaining T of coriander.
Grill the chicken breasts for about 6 minutes on each side until thoroughly cooked.