Place each chicken breast between 2 sheets of greaseproof paper and pound it gently until the fillet is about 15mm thick.

To make the marinade, place all the ingredients in a food processor and process until they are well combined but not completely puréed.

Marinate the chicken breasts for 1 hour.

Meanwhile, make the relish.

Use a sharp knife or Japanese mandolin to finely slice the cucumber and celery.

In a bowl, whisk the oil, vinegar and mustard together, then season with salt and pepper to taste.

Fold in the yoghurt. Add the cucumber, celery, tomato and mint leaves, and mix to combine.

Heat a barbecue or grill pan to hot.

Remove the chicken from the marinade and grill it, skin side down, for 2 minutes, then turn and cook for a further minute or until just cooked through.

Rest in a warm place for about 1 minute.

Place the chicken pieces on a platter, and serve with the relish on the side.