Preheat the oven to 400 degrees F. Cook the chorizo in a large cast-iron skillet over medium heat, breaking up the meat with a wooden spoon as it renders, about 5 minutes. Add the onion, serrano and garlic and continue cooking until the chorizo is crisp and the onion is translucent, 5 to 7 minutes. Remove the mixture from the skillet and transfer to a bowl. Toss the cheeses with the flour in a separate bowl.
Add the beer to the skillet, stirring and scraping up any browned bits from the bottom of the skillet. Whisking constantly, add the cheese mixture a little bit at a time, whisking until smooth and well blended. Stir in the beans, chiles and chorizo mixture.
Place the skillet in the oven and cook until the queso is hot and bubbly, about 5 minutes. Garnish with scallions and tomato and serve with tortilla chips.
Cut 8 flour or corn tortillas into wedges; fry in 350 degrees F vegetable oil, a few at a time, until crisp, about 30 seconds per side. Drain on paper towels; season with salt, cumin and a squeeze of lime juice.