In a large mixing bowl, open and drain one can of tuna packed in olive oil. Using a fork, gently flake the tuna into bite-sized pieces.

Add one cup of rinsed cannellini beans, half a finely chopped red onion, and a handful of freshly chopped parsley to the bowl with the tuna. Toss together gently.

In a separate smaller bowl, whisk together the juice of one lemon, olive oil, Dijon mustard, and dried oregano until well blended.

Pour the vinaigrette over the tuna and bean mixture, gently toss to coat without mashing the beans.

Season your salad with salt and freshly ground black pepper to taste. Serve immediately or let it chill for 30 minutes.