8 ounces green beans, cut into 1 to 2-inch pieces (about 2 cups)
1 head Romaine lettuce, torn
1 (15-ounce) can cannellini beans, drained and rinsed
1/2 cup pitted black olives
1/2 red onion, cut into slivers
1 lemon, juiced
1/4 cup extra-virgin olive oil
1 teaspoon kosher salt
1 teaspoon freshly ground black pepper
1 ounce shaved Parmesan (about 1/2 cup)