2tablespoons neutral oil (such as safflower or canola)
1pound ground beef
1medium yellow onion, finely chopped
2teaspoons ground cumin
2teaspoons dried oregano
1½teaspoons chili powder
3garlic cloves, finely chopped
1(15.5-ounce) can pinto beans, drained, ½ cup bean liquid reserved
Corn chips (preferably Fritos), as desired
2cups/4 ounces coarsely grated Colby or Cheddar cheese, plus more for serving
1small head iceberg lettuce, shredded
1large beefsteak tomato, chopped
2limes, cut into wedges
½cup sour cream
Hot sauce, to serve
In a large cast-iron or stainless skillet over medium-high, heat the oil until it shimmers. Add the beef and press it into one even layer. Sprinkle evenly with salt and onion, and cook, undisturbed, until the beef is deeply browned on the bottom and still slightly pink on top, and the onions have wilted, 5 to 7 minutes. If there is an excess of fat in the pan at this point, tip the skillet and use a spoon to discard it.
Sprinkle over the cumin, oregano, chili powder and garlic. Using a wooden spoon, break the meat into small crumbles and stir. Cook, stirring frequently, until the spices are aromatic and the meat has cooked through, about 2 minutes.
Add the beans and reserved bean liquid, and use the spoon to scrape up any browned bits. Simmer until mostly reduced, about 2 minutes. Remove from heat, taste and add more salt if needed.
Arrange some corn chips evenly across the bottom of four serving plates. Evenly divide the meat mixture, cheese, lettuce, tomato and avocado on top of the chips. Squeeze lime juice over the top and lightly sprinkle with salt. Top each salad with a handful of crushed corn chips, a big dollop of sour cream, and extra cheese. Serve right away with hot sauce alongside.