Preheat oven to 400ºF.
Heat a large Dutch oven over medium heat. Season pork liberally with salt, cumin and coriander. Add oil to the pot and let it get hot. Add pork and brown for about 3-5 minutes.
While pork is browning, toss jalapeños, poblanos and tomatillos with oil, salt and pepper and place on a cookie sheet. Bake for 10-15 minutes.
Add garlic and onion to the pot with the pork and sweat for 2 minutes. Remove vegetables from oven and pulse in a food processor. Add to pot with beer and stock and simmer for 1 hour or until pork is tender.
Serve with any combination of pickled red onions, rice, lime wedges, Cotija cheese, cilantro and tortilla chips.