Slice each chicken breast into 5-6 long strips and season with salt and freshly ground black pepper.
Heat the olive oil in a frying pan and fry the chicken breasts over a medium heat for 3-5 minutes, turning occasionally, until lightly browned.
Pour the stock over the chicken. Bring to the boil, then reduce the heat and simmer for 3-5 minutes. Add the butter and lemon juice and stir. Simmer for 5-7 minutes, until the chicken is cooked through. (No pink should remain when the meat is cut into. If any pink remains, cook further.) Keep warm.
Warm the tortilla wraps in the frying pan for 1-2 minutes on each side. Remove and keep warm.
For the dressing, mix the yoghurt and chopped mint into a clean bowl and mix well.
To serve, divide the chicken pieces between the flatbreads. Stuff with fresh grated carrot, mixed salad leaves, sliced tomato and any sauces. Dollop on the yoghurt dressing.