With a taste similar to cucumber, chayote squash gives this salad a cool, refreshing flavor.
Quarter squash, and discard inner membranes. Cut each squash quarter lengthwise into four pieces, and transfer to a steamer basket.
Bring 2 cups water to a boil in a large saucepan. Place basket in saucepan; reduce heat to low so that water simmers. Cover; steam squash until tender and translucent, about 30 minutes. Transfer to a medium bowl to cool. Toss with oil and parsley; season with salt and pepper. Chill until cold, 1 to 2 hours. Serve salad garnished with parsley leaves, if desired.