Dice chicken into very small pieces.
Dice onion and olives to slightly smaller pieces than the chicken.
Mix all of the ingredients except the salt in a bowl large enough to both accommodate the volume and with room to spare for stirring and mixing.
Stir until components are evenly distributed
Add salt a pinch at a time, stirring to distribute between additions and tasting before adding more.
Refrigerate for at least an hour for the flavors to set.
Makes enough filling for 4-6 sandwiches, depending on size.