This salad is great for a picnic, or it can be served as a side for lunch or dinner.
Bring a large saucepan of salted water to a boil. Add lima beans and cook, stirring occasionally, until tender, about 4 minutes. Drain, rinse with cold water (to stop further cooking), then drain again, and pat dry with paper towels.
Transfer lima beans to a bowl. Stir in oil, lemon zest, and lemon juice; season with salt and pepper. Divide among four serving plates, and sprinkle with Parmesan.