Bring 6 cups water to boil in large saucepan. Add beans; boil 2 minutes. Remove from heat. Let stand, covered, 1 hour. Drain beans, reserving 3 cups of the cooking liquid.
Heat oil in 5-quart Dutch oven or saucepot on medium-high heat. Add onion, bell pepper and chorizo; cook and stir 7 minutes or until vegetables soften. Reduce heat to medium-low. Add oregano, cumin, garlic powder and bay leaves; cook and stir 1 minute or until fragrant.
Stir in chicken broth, drained beans and reserved 3 cups cooking liquid. Bring to boil. Reduce heat to medium-low; simmer, uncovered, 3 hours or until beans are tender and soup has thickened, stirring occasionally and skimming off any foam that rises to the surface. (If mixture gets too thick and beans are not covered by liquid, add water to cover.) Stir in vinegar. Season with salt, if desired.
To serve soup, ladle into serving bowls. Garnish with avocado, red onion and a drizzle of Mint Crema (recipe follows).