To a blender add tomatillos, onion, cilantro, ground cumin, oregano and garlic cloves with one cup of chicken broth, blend until smooth. Season to taste with salt and pepper; add to slow cooker along with remaining chicken broth and chicken breast. Cover and cook on Low for 6 hours. Carefully with tongs remove chicken breasts, shred and return to slow cooker along with hominy. Cook an additional 30 minute to warm hominy through, Ladle posole into bowls; top with avocado, cilantro and serve with lime wedges.