Preheat broiler.
Place a rack in the center of the oven, arrange chilies, tomatillos and onions on a baking sheet, coat with cooking spray and broil, turning pan occasionally, until evenly blistered and charred and tender. Let cool to handle.
Place about 1/2 to 1 cup stock in a food processor with the tomatillos and onions. Peel skins away from peppers and seed them, add them to processor and purée.
Bring meat to room temperature and pat dry.
Heat a Dutch oven over medium-high heat with the oil until smoking. Brown and crumble the beef then add garlic, salt, pepper, cumin and coriander, and stir to toast. Stir in peppers and onions, the tomatillo purée and remaining stock. Simmer a few minutes to thicken and adjust seasoning.
Ladle chili into shallow bowls and top with a squeeze of lime, some red onions and cilantro, Serve with chips alongside.