Heat a frying pan or grill to high. Rub the chicken breasts with the oil and then season with freshly ground black pepper. Put the chicken in the pan and turn the heat down a little, then cook for about 7 or 8 minutes per side or until the chicken is completely cooked through with no pink showing.
Meanwhile, put the chopped avocado, sweetcorn, watercress and tomatoes in a large bowl with the torn pitta breads. Whisk the dressing ingredients together in a jug. Season to taste.
When the chicken is cooked, leave it to cool for a few minutes. Toss the dressing with the salad, then shred the cooked chicken with forks and add to the salad. Mix well, so all the ingredients are coated in dressing, and serve.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.