In a medium mixing bowl, add the drained tuna and chickpeas. Use a fork to lightly flake the tuna and gently mash about half the chickpeas, leaving the rest whole for better texture.

Add the finely chopped red onion, diced cucumber, halved Kalamata olives, and fresh parsley to the bowl. Mix gently to combine.

In a small bowl, whisk together the extra virgin olive oil, fresh lemon juice, and Dijon mustard until well emulsified.

Pour the dressing over the tuna and vegetable mixture. Stir gently until everything is well combined and evenly coated.

Season with salt and black pepper to taste. Remember that the olives are salty, so start with less salt than you think you need.

Serve immediately, or for even better flavor, refrigerate for 30 minutes to let everything marry together.