Soak the cashew nuts for a least 4 hours (preferably overnight).
Mix the cashew's in a blender with the rest of the ingredients until you have a creamy texture.
Put the oven on 175°C/350 F, chop the sweet potato into fine slices. Add them to a oven safe tray, mix them in the vegetable oil. Bake for 1 hour.
Chop and mince the onion, chili and the garlic. Cut the broccoli into similar pieces.
Fry the onions for a few minutes in a casserole and add the garlic and chili to let i go for a few more minutes.
Add the water and the vegetable broth, bring to a boil.
Add the broccoli let it boil for approximately 5 min until it is al dente.
Mix it with a hand blender or in a ordinary blender until you have a nice green smooth soup.
Taste the soup and add some lemon juice, salt and cayenne pepper until it's delicious.
Serve with the cashew cream.