How to Make It
Bring a large pot of water to a boil over high heat. Add pasta; cook 5 minutes. Add beans; cook an additional 3 minutes or until beans are crisp-tender and pasta is done. Drain and rinse under cold water; drain.
While pasta water comes to a boil, combine oil, juice, pepper, and salt in a large bowl, stirring with a whisk. Add tomato, oregano, and olives; let stand 10 minutes. Stir in pasta mixture and lettuce. Divide among 4 plates; top evenly with tuna.