Drain or cook tuna, then flake it gently into medium-sized pieces to maintain texture and avoid mushiness.
Finely chop celery, onion, cucumber, and parsley so each bite has a balanced mix of crunch and flavor.
Mix mayonnaise, Greek yogurt, mustard, lemon juice, zest, and seasonings until smooth and creamy.
Fold tuna into the dressing gently, ensuring it stays chunky and well-coated.
Add chopped vegetables and herbs, mixing just enough to distribute evenly without breaking them down.
Chill the salad for 15–20 minutes to allow flavors to develop fully before serving.