In a bowl, mix together the herb seasoning, lemon juice and oil. Add the chicken and peppers and toss well in the marinade.
Preheat a non- stick frying pan and add the chicken mixture. Toss in the pan and then leave to cook for 2 minutes before tossing again. Reduce the heat slightly and cook for a further 10 minutes, turning the chicken and peppers occasionally. Once the chicken has cooked and no pink remains remove from the heat.
Place the spinach and parsley in a large bowl and add the cooked chicken mixture. Toss carefully and season with pepper. Open each flatbread and spread ½ tablespoon of mayonnaise over. Fill each flatbread with the mixture and serve with a little more parsley to garnish.
TIP: If you have time, marinade the chicken and peppers for a few hours before cooking.