Heat a medium skillet over medium-high heat and cook the ground beef, breaking it into small crumbles as it browns, then drain away the fat. The beef should be deeply browned with no pink remaining, and the skillet should no longer have a greasy pool around the meat.

Stir the taco seasoning and ½ cup water into the drained beef, then simmer uncovered over medium heat for 5 minutes before folding in the beans. The liquid should bubble steadily and reduce into a thick sauce that clings to the meat rather than collecting at the bottom of the skillet.

Take the skillet off the heat and let the seasoned beef sit for 5 minutes, then place the lettuce in one large salad bowl or divide it among serving bowls. When the strongest steam has faded, the meat is warm enough to layer over chilled lettuce without instantly softening it.

Spoon the beef mixture over the lettuce and add the tomatoes, cheddar, avocado, and desired toppings, then finish with tortilla chips, salsa, and sour cream. The finished salad should have distinct layers of cool greens, warm beef, creamy toppings, and crisp chips.