Heat the oil in a large pot over medium heat. Add the onion and cook until caramelized, stirring occasionally. Add the kale and cook until wilted. Stir in the yam, paprika, curry powder and bay leaf; cook until the spices become more fragrant, about a minute. Add the broth and bring to a simmer. Cook 30 minutes or until kale and sweet potato are tender. Purée 1 can beans with 3/4 cup water in a blender or food processor. Add purée and remaining beans to the soup. Simmer 10 minutes, then stir in the vinegar. Remove the bay leaf and taste for seasoning. Add salt and pepper as needed. Sprinkle each serving with more paprika if you want. Try adding some barley to the finished soup to make it more of a meal!