Preheat oven to broil. Place chiles on pan and place in oven on top rack. Broil until skin is charred. Flip chiles and continue broiling until other side is charred. Remove from oven and cover tightly with aluminum foil.
Once chiles have cooled enough to handle, remove skin, stems, and seeds and discard.
Reduce oven temperature to 425 degrees F. On a baking sheet, toss tomatillos, onion, and garlic in olive oil. Place in oven and roast until soft and browned. Allow to cool.
Add tomatillos, onion, garlic, and hatch chiles to blender. Blend until smooth. Add cilantro, salt, and lime juice and pulse until combined. Enjoy!