Preheat the oven to 190°C.
Put the beetroot (unpeeled) into a roasting dish.
Remove the seeds and membrane of the squash, then cut it into wedges (unpeeled) and arrange them between the beetroot. Tuck the garlic, chilli and onion between them (again, unpeeled).
Mix the spiced oil then brush the veggies with it.
Cover with foil, then bake for about 30 minutes, until the vegetables are soft. Let them cool.
Refrigerate until you’re ready to make the soup.
Remove the skins of all the veggies and put their flesh into a saucepan. If you’re using the chilli, remove the seeds. Pour over the stock and bring to a simmer.
Add the coriander leaves, turn off the heat and whiz with a hand-held blender into a smooth, silky soup.
Reheat if necessary - you can some green veggies or drained tinned beans for a hearty meal.
Serve warm.