4 lbs bone-in chicken thighs
2 tbsp vegetable oil
1 onion chopped fine
3 garlic cloves minced
1 tsp oregano
4 1/2 cups chicken broth
12 ounces tomatillos quartered
2 1/2 cups cilantro (2 bunches)
2 15 oz cans hominy drained and rinsed
Adjust oven to lower -middle rack. Heat oven to 300. Salt and pepper chicken. Heat 1 Tbsp oil in dutch oven over medium-high until just smoking. Brown half the chicken, about 5 minutes per side. Transfer to a plate. Brown other half of chicken in 1 Tbsp oil. Let cool slightly and remove skin.
Pour off all but 1 Tbsp of fat; add onion and 1/4 tsp salt. Cook until softened about 5 minutes. Add garlic and oregano and cook until fragrant, about 30 seconds. Stir is 4 cups of broth scraping browned bits and bring to a simmer. Nestle chicken into pot along with juices. Cover and put pot in oven. Cook for 1 hour.
Remove pot from oven, transfer chicken to cutting board and let cool. Meanwhile, process tomatillos, jalapenos, cilantro and 1/2 chicken broth in blender, about 30 seconds. Stir tomatillo sauce and hominy into soup, bring to a simmer over medium heat until flavors meld, about 15 minutes.
Shred chicken, discard bones. Stir chicken into soup and cook until heated through, about 2 minutes. Season with salt and pepper.
Serve with avocado, crumbled tortilla chips, cheese, and sour cream.