Heat the white wine vinegar, sugar and coriander seeds in a large saucepan until the sugar is dissolved. Meanwhile, shred the Chinese cabbage, slice the carrots into matchsticks and slice the radishes. Once the sugar is dissolved in the vinegar, remove from the heat and pour over the cabbage and carrots. Leave to pickle for 10 minutes.
Heat a large griddle pan on the hob. Butterfly the chicken breasts by slicing halfway through the thicker part of the breast, and open out.
Put a small drizzle of olive oil in a bowl and sprinkle in the jerk seasoning. Massage the oil and jerk seasoning into the chicken. Season with salt and pepper. When the griddle pan is smoking hot, place the chicken on the griddle and cook for 3-4 minutes on each side, or until cooked through. Remove the chicken from the heat, cover and set aside to rest.
Drain the vegetables, and slice the chicken into strips. Wrap inside the flatbreads.