Preheat your oven to broil. Slice the peeled and rinsed tomatillos in half through the horizontal center and arrange on a lightly oiled baking dish with the skin sides up.
For making the chili verde, heat a large pot and add a bit of olive oil. Season the pork shoulder with ancho powder, cumin, salt and pepper, then add the pork. Sear the cubes to brown the pork on all sides, until each side is nicely browned, stirring.
Add the onions and stir. Cook them down to soften.
Stir in the garlic and Mexican oregano and cook.
Add the reserved verde sauce along with chicken stock. Bring to a quick boil, then reduce the heat and cover. Simmeruntil the pork is fork tender.
Remove the chili verde from the heat and stir in the chopped cilantro and lime juice.