1) Heat the oil in a large soup pot over a medium-high heat. Add the onions, pepper and carrots and cook, stirring until the vegetables soften, about five minutes. Add the cayenne, black pepper, garlic and ginger and cook for one minute more. Stir in the sweet potato, broth, and tomatoes and bring to a boil. Reduce the heat to medium-low and simmer until the potatoes are tender, about 20 minutes.
2) Puree the soup in the pot using an immersion blender or in a regular blender in two batches and return the soup to the pot. Add the peanut butter and honey and stir, over low heat, until the peanut butter melts. Serve warm, garnished with the spring onions.
* Cook's Note: When blending hot liquids, remove liquid from the heat and allow to cool for at least five minutes. Transfer liquid to a blender or food processor and fill it no more than halfway. If using a blender, release one corner of the lid. This prevents the vacuum effect that creates heat explosions. Place a towel over the top of the machine, pulse a few times then process on high speed until smooth.