Heat ¼ cup of water in a large saucepan over medium. Add onion, cover, and cook 5 minutes or until softened. Add bell pepper and garlic, cover; cook 5 minutes or until softened. Stir in ginger, cumin and cayenne; cook, stirring, 30 seconds. Add sweet potatoes, stirring to coat. Stir in tomatoes, miso paste and 1¾ cups broth. Bring to a boil, reduce heat to low and simmer 20 minutes. Stir in beans; simmer 10 minutes or until vegetables are soft and heated through. In a small bowl, combine peanut butter and remaining ¼ cup broth until smooth; stir into stew. If a thicker consistency is desired, puree 1 cup stew in a blender or food processor and stir back into the pot. Taste and adjust seasonings, if needed. Ladle into bowls, sprinkle with chopped peanuts and black cumin.