Place black beans in large pot with enough cold water to cover by 3 inches and let soak overnight.
Drain beans. Return beans to pot. Add 20 cups of water and pepper and bring to a boil. Reduce heat and simmer until beans are tender, stirring occasionally, about 1 1/2 hours. As an alternatime, cover beans by 3 inches with water, add black pepper and bring to a boil for 20 minutes, cover and let sit for two hours. Check to insure tenderness. Drain beans.
Melt butter in same pot over medium heat. Add anaheim chilies, chopped onion (save some for garnish), celery, bell pepper, leek, garlic and oregano. Cook until vegetables soften, stirring occasionally, about 10 minutes. Reduce heat to low. Add flour, chili powder, cumin, coriander, cayenne pepper, red pepper flakes, salt and sugar and cook 5 minutes, stirring frequently. Add 8 cups of stock and bring to a simmer, stirring frequently. Puree 3 cups of corn with remaining 1 cup of stock in food processor. Add puree to chili. Mix in black beans, turkey and remaining 2 cups of corn. Simmer chili 20 minutes, stirring occasionally. Can be prepeared 1 day ahead. Cover and refrigerate. Reheat before serving.
Ladle chili into bowls. Serve with cheese, chopped onion, sour cream and cilantro.