1. Melt the butter over medium-high heat in a large soup pot. Add the onions, garlic, and bay leaf, cook stirring occasionally until the onions are slightly soft, about 3 minutes. Add the sweet potatoes and cook until soft around the edges, another 2 minutes. Scatter the flour over the vegetables and stir until the flour is absorbed into the mixture, 1 minute.
2. Add the broth to the pot, whisking until smooth. Bring the soup to a boil over high heat and season with 2 teaspoons salt and some pepper. Once the soup boils, reduce the heat to medium-low, cover, and cook until the potatoes are tender, about 10 minutes.
3. Season the chicken with salt and pepper, stir into the soup and cook until just cooked through, about 4 minutes. Add the cilantro and divide the soup into 4 serving bowls. Top each soup with sour cream and chipotle hot sauce as desired. Serve.
Copyright 2010 Television Food Network, G.P. All rights reserved