In a large saucepan, saute the onion and garlic in the oil, stirring until onions are transparent. Add the celery, carrots, potatoes, leeks and broth. Bring the soup to a boil, reduce the heat, cover the pan, and simmer the soup until the vegetables are tender, about 15 minutes. Stir in the cayenne, black pepper, salt, peanut butter and tahini. Transfer the soup to a blender and puree it. Garnish and serve.
Recipe courtesy of Island Wellness Caf�, Key West