Tuna and white bean salad

Ingredients

• 1 can (15 to 15 ½ ounces) white cannellini beans,<br> rinsed, drained
• 1/2 cup thinly sliced red onion, halved
• 1 can (6 ounces) tuna in olive oil (drain; reserve oil)
• 1 cup diced plum tomatoes
• 1/2 cup pitted Kalamata olives
• 2 tablespoons chopped Italian parsley
• 1 tablespoon lemon juice
• ½ teaspoon grated lemon zest
• ¼ teaspoon each salt and freshly ground black pepper
• 2 cups torn arugula leaves
• 4 thick flatbreads
• recipeIngredient ends