They were taken to Europe by Spanish explorers and from there were introduced to parts of Asia. A choko is also known as chayote, vegetable pear or mango squash. They grow on a climbing plant and look a bit like a pear.
Cut the choko in half and remove the seed. Some people eat the seeds and they have a nutty flavour. If boiling or steaming, leave the skin on to retain the flavour; cook for about 15-20 minutes or until tender.