2 5- to 6-ounce cans water-packed chunk light tuna, drained and flaked (see Note)
1 large red bell pepper, finely diced
½ cup finely chopped red onion
½ cup chopped fresh parsley, divided
4 teaspoons capers, rinsed
1½ teaspoons finely chopped fresh rosemary
½ cup lemon juice, divided
4 tablespoons extra-virgin olive oil, divided
Freshly ground pepper, to taste
¼ teaspoon salt
8 cups mixed salad greens
Combine beans, tuna, bell pepper, onion, parsley, capers, rosemary, ¼ cup lemon juice and 2 tablespoons oil in a medium bowl. Season with pepper. Combine the remaining ¼ cup lemon juice, 2 tablespoons oil and salt in a large bowl. Add salad greens; toss to coat. Divide the greens among 4 plates. Top each with the tuna salad.