Set a steamer basket insert into a large saucepan and fill with water to a level just below the steamer. Bring to a boil. Add green beans, and steam to your desired degree of tenderness, or about 5 minutes.
Once the beans have cooked, transfer them to a serving bowl. Toss with olive oil, garlic, salt, pepper, white wine vinegar, and Parmesan cheese. Let stand for 10 minutes. Remove garlic slices and garnish with parsley before serving.
