Place water in 4-quart saucepan. Cover; cook over medium-high heat until water comes to a boil (2 to 3 minutes). Add green beans. Cover; continue cooking until beans are crisply tender (4 to 6 minutes). Drain.
Add butter, oil and olives to green beans. Cook, stirring occasionally, 3 minutes. Add tomatoes, oregano, salt and pepper. Cook, stirring occasionally, 1 minute. Top with feta cheese, if desired. Serve immediately.
You can substitute 1 teaspoon dried oregano leaves if you do not have fresh.