Preheat the broiler. Put the poblanos on a broiler pan and broil, turning occasionally, until charred all over, about 10 minutes. Transfer to a bowl, cover with a plate and let steam until cool enough to handle, about 10 minutes. Scrape off the charred skin with a paring knife and remove the stems and seeds; chop the peppers and set aside.
Heat the olive oil in an 8- or 9-inch cast-iron skillet over medium heat; add the chorizo and cook, breaking up the meat with a wooden spoon, until cooked through, about 5 minutes. Add the scallions and poblanos and cook until the scallions are wilted, about 2 minutes. Add the flour and cook, stirring to coat, 1 minute.
Add the lager and bring to a boil; cook until thickened, about 1 minute. Add the cheese, a handful at a time, stirring until melted before adding more. Transfer the skillet to the broiler and broil until browned and bubbling, 1 to 2 minutes. Serve with chips.