Drain and flake canned tuna into a large bowl.
Add chopped tomatoes, red onions, and cucumbers.
Toss in drained cannellini beans and black olives.
Drizzle with olive oil and lemon juice.
Season with salt, pepper, and oregano.
Mix in fresh basil leaves for added flavor.
Gently toss all ingredients together.Serve the salad over a bed of arugula or spinach.
Enjoy your refreshing and healthy Tuscan tuna salad!