Cut pork into 1/2 inch cubes and add to a large ziplock bag.
Add salt, pepper, garlic powder, chili powder, cumin and olive oil to the bag. Seal the bag and move pork pieces all around to ensure they are all coated. Marinade for at least 30 minutes.
Meanwhile, add tomatillos, onion, garlic, peppers, oregano, and cilantro to a blender (this will need to be done in batches). Blend well and set aside.
Heat a Dutch oven over medium high heat. Add pork and the marinade. Sear pork on all sides.
Stir in chili verde sauce chicken stock. Bring to a boil. Reduce heat to the lowest setting and cover. Simmer for 2 – 3 hours stirring occasionally.
