In a small bowl, combine parsley, basil, capers, minced garlic, and anchovy paste. Add red pepper flakes and black pepper to taste. Pour in olive oil and vinegar, stirring until well mixed. Allow to rest for 5 minutes.

Rinse cannellini beans under cold water until liquid runs clear, then drain. In a medium bowl, combine beans, cherry tomatoes, olives, and red onion. Toss gently with a pinch of salt.

Drizzle the salsa verde over the salad mixture. Toss gently with a spatula or large spoon without mashing the ingredients.

Top with Parmesan shavings. If desired, add tuna and serve immediately with bread on the side.