Preheat oven to 425 degrees F. Grease a baking sheet. Place tomatillos, onion, jalapeno and garlic on baking sheet and roast 25 minutes. Remove from oven and set aside.
Place a enameled cast iron skillet over medium heat. Add the cumin and pumpkin seeds to the skillet and toast, shaking the pan periodically, for 5 minutes. Pour toasted seeds over roasted vegetables and stir to combine. Stir in ½ cup chopped cilantro and oregano.
Return pan to heat and add coconut oil. When shimmering, add the pork chunks, keeping space between each piece to ensure a good sear (crowding will cause pork to steam). Sear pork chunks on both sides, transfer to a plate. Continue with remaining pork in batches.
Return seared pork to pan and top with vegetable mixture. Cook over medium-low heat until pork is cooked through (145 degrees F). Season with high quality sea salt and freshly ground black pepper