Whisk together yogurt, lemon juice, tahini, sea salt, pepper, and parsley in a small bowl until smooth and creamy.
To a separate medium bowl add tuna, chickpeas, red onion, and celery. Pour yogurt mixture over top and stir until combined.
Create pitas: add two tablespoons tuna and chickpea mixture into pitas. Garnish with arugula and cherry tomatoes. Fold and devour!