Roast the poblanos under the broiler for 10 minutes, turning once, or until blackened. Place in a paper bag for about 20 minutes. After this, the skins should come right off. Then seed and dice the peeled poblanos.
In a large soup pot or Dutch oven, heat up 1 tablespoon of the bacon grease on medium-low heat. Lightly salt and pepper the cubed pork and add to the pot, browning on each side, about 2-5 minutes per side. You may have to do this in batches. Once browned, transfer the pork to a large bowl, pouring into the bowl the pan juices.
Return the pot to the stove and heat up the remaining tablespoon of bacon grease on medium-low heat. Add the onion and cook until translucent, about 5 minutes. Add the garlic and cook for 30 more seconds.
Return the pork and its juices to the pot, along with the poblano chiles, Serrano chiles, jalapeño chiles, tomatillos, chicken broth, Mexican lager, cumin, oregano, and 1/2 cup of the chopped cilantro. Turn the heat up to high, bring to a boil and then turn the heat down to low and gently simmer uncovered for 2 hours, stirring occasionally and skimming any fat from the surface.
After 2 hours, add the rest of the cilantro and taste and adjust seasonings, adding more if needed. Continue to cook uncovered for another hour to 1 hour or until the pork is tender.
To thicken the chili, on a separate dish, mix the masa harina with some of the chili liquid until a thick paste is formed. Slowly stir this into the chili until it’s well incorporate without any lumps. Continue to cook for another 15 minutes. Goes great with sour cream and tortillas.
Notes
You can use fewer Serrano and jalapeño chiles if you want it to be less fiery.