Cut the onion into a relatively small dice and chop the squash into roughly bite-sized pieces.

Heat the oil slightly in a pan and add the onion. Cook for 2-3 minutes over a medium-high heat until it is starting to become translucent. Be careful not to let it brown (don't have the oil too hot before you add the onion and turn down the heat if it looks like it is browning).

Add the squash, stir so they take on a little of the oil and then turn down the heat and cover the pan. Allow the squash to cook, stirring every 2-3minutes for around 10 minutes.

Add the lemongrass and ginger, stir them through, then add the stock. Increase the heat and cover to bring to a boil then reduce the heat to a simmer.

Allow to cook for around 10 minutes - the exact time will depend on the squash and how big your chunks are - until the squash is tender when you test it with a knife.

Blend the soup then stir through the coconut milk.