In a medium saucepan, heat the olive oil and add the onion, garlic and jalapeno.
Cook on a medium heat for 3-5 minutes until soft.
Peel and chop the chayote into small pieces.
Add the chayote to the saucepan and cook for another 5 minutes, stirring occasionally.
Add the vegetable stock, season with the salt and pepper, then bring to the boil and cover with a lid. Simmer for 15-20 minutes until the chayote is soft.
Remove from the heat and allow to cool slightly before blending.
Blend the soup with either a hand blender or upright blender until smooth.
Return to the saucepan and adjust for seasoning. Reheat and serve.
Serve with chopped green onions.