Drain the canned tuna thoroughly and place it in a medium mixing bowl. Use a fork to gently flake the tuna into smaller pieces so it mixes easily with the dressing and vegetables.

Add the diced celery, chopped red onion, and dill pickles to the bowl with the tuna. These ingredients provide the signature crunch and flavor that classic tuna salad is known for.

In the same bowl, add mayonnaise, lemon juice, Dijon mustard, garlic powder, salt, and black pepper. Stir everything together gently until the tuna and vegetables are evenly coated with the creamy dressing.

Fold in the chopped parsley and taste the salad to adjust seasoning if needed. Chill the tuna salad in the refrigerator for about 15–20 minutes before serving so the flavors blend together.