1. Heat olive oil in a large saucepan over medium heat. Add the onion, cover and cook until softened, about 5 minutes. Add the bell pepper and garlic, cover, and cook until softened, about 5 minutes. Stir in the brown sugar, ginger, cumin, cinnamon and cayenne and cook, stirring, for 30 seconds. Add the sweet potatoes and stir to coat. Stir in the tomatoes, stock and salt to taste. Bring to a boil, then reduce the heat to low and simmer until the vegetables are soft, about 30 minutes.
2. About 10 minutes before the end of the cooking time, stir in the kidney beans and simmer until heated through.
3. Place the peanut butter in a small bowl and blend in about 1/4 cup of the broth, stirring until smooth, then stir it into the stew. If a thicker consistency is desired, puree 1 cup of the stew in a blender or food processor and stir back into pot.
4. Taste and adjust seasonings. Sprinkle with chopped peanuts and serve.