Start with the tuna and flake it up in your mixing bowl so there are no chunks. Add olive oil mayo or Greek yogurt depending on your preference and ranch dressing. Stir thoroughly. Add chopped celery, olives with pimentos, and onions. Mix thoroughly. Add salt, pepper and garlic powder to taste. Taste as go along to adjust for your own preferences.
For extra crunch add some chopped water chestnuts and for an even more Mediterranean feel add feta cheese throughout.