Add remaining 1 teaspoon oil to pan; swirl to coat.
Add onion and bell pepper; cook 3 minutes, stirring occasionally. Stir in oregano and next 4 ingredients (through salt); cook 30 seconds. Stir in stock and beans. Bring to a boil; reduce heat, and simmer 3 minutes. Stir in cooked chorizo and juice. Ladle 1 1/4 cups soup into each of 4 bowls; top each serving with 1 tablespoon sour cream and 1 tablespoon cilantro.