Peel onion and chop into fairly large chunks. Similarly peel and chop sweet potatoes, keep them about 2-3cm cubes so they don't take too long to cook.
Heat your wok or pan and spray with the cooking oil spray. Add the onions and potatoes and keep them moving for a couple of minutes. Season with salt and pepper (the himalayan crystal sea salt should also stop the onion from going too dark).
.After about three minutes, add the Thai curry paste and keep stirring for another few minutes to make sure everything is coated.
Add the vegetable stock and coconut milk. You may not need the entire pint of stock, the stock and milk together should almost cover the vegetables.
Cook on fairly low heat until sweet potatoes are cooked (about 20 to 25 minutes), then blitz till smooth.
Can eat straight away, keep in fridge and reheat or freeze till needed!