Finely dice the celery, mince the red onion, and dice the dill pickles into small, uniform pieces. Chop the fresh parsley. This mise en place ensures all components are ready to incorporate and helps the flavors distribute evenly throughout the salad. Set the prepped vegetables aside on a cutting board or in small bowls.

In a medium bowl, whisk together the Greek yogurt, mayonnaise, Dijon mustard, and fresh lemon juice until smooth and well combined. This creates an emulsified dressing that will coat the tuna evenly. I prefer to make the dressing first so the mustard and lemon juice can slightly mellow and blend together before the tuna is added.

Add the drained tuna to the bowl with the creamy dressing from Step 2, breaking it apart gently with a fork as you fold it in. Add the garlic powder, celery seed, sea salt, and freshly cracked black pepper, stirring gently to combine. The tuna should be broken into bite-sized pieces but not overmixed—keep some texture intact.

Gently fold the prepped vegetables from Step 1 into the tuna mixture until evenly distributed. Taste and adjust seasonings as needed—I like to add an extra pinch of sea salt and cracked pepper if the salad feels a bit mild. The salad is now ready to serve immediately or can be refrigerated for up to 2 days.

Serve the tuna salad on crusty bread, crackers, or over fresh greens for a lighter option. The creamy, tangy mixture is versatile and works well in sandwiches, as a lettuce wrap, or on a bed of mixed vegetables.