Open both cans of tuna and drain the water completely, pressing with the back of a spoon to remove excess moisture.

Place the drained tuna into the mixing bowl and use a fork to break it into small, bite-sized flakes.

Finely dice the celery and red bell pepper and mince the red onion, ensuring uniform small pieces.

In a small bowl, whisk together Greek yogurt, Dijon mustard, fresh lemon juice, sea salt, black pepper, and cayenne pepper if using.

Fold the diced celery, red bell pepper, and red onion into the flaked tuna, mixing gently to distribute evenly.

Pour the yogurt and seasoning mixture over the tuna and vegetables, then fold gently with a spoon until evenly coated.

Stir in the chopped fresh dill and taste, adjusting salt or lemon juice if needed.

Refrigerate the salad for at least 10 minutes to allow the flavors to meld, then serve cold.