In a medium bowl, combine mayonnaise and Dijon mustard. Add chicken, peppers and celery. Add rice and mix lightly. Season with salt and pepper to taste, if desired. Line pita pockets halves with lettuce leaves and spoon in salad.
HELPFUL TIPS: 1) Cook extra white or brown rice. It can be stored in the refrigerator up to six days; or, the freezer for up to six months.
2) Using a non-stick skillet to brown meat and other vegetables helps reduce the need for added oil.
3) Reheat pita pockets in the microwave for about 10 to 20 seconds to soften.