In a mixing bowl, combine crabmeat, snow peas, water chestnuts, bell pepper and green onion; set aside.
In a small bowl or cup, combine mayonnaise, mustard, lemon juice and curry powder.
Combine crab mixture with mayonnaise mixture; blend well.
Place 1 slice of lettuce and 1 slice of cheese in each pita half; spoon crab mixture evenly into pitas.
Place pita on plastic wrap or aluminum foil and seal; refrigerate overnight or until ready to serve for lunch.