Brown and wilt. In a large cast-iron skillet over medium-high, cook the ground beef, breaking it up, until it starts to brown.
1 lb lean ground beef
Add the onion and the cabbage. (It will look like an absurd amount of cabbage. Trust it.) Cook, stirring, until the cabbage wilts down and the beef is cooked through, 8 to 10 minutes.
1 ea small onion, 4 cups finely chopped purple cabbage
Stir in the taco seasoning, the Ro-Tel with its juices, and one Ro-Tel can of water. Bring to a simmer.
2 tbsp Penzey’s Bold Taco seasoning, 10 oz Ro-Tel, 10 oz water
Simmer, stirring now and then, until the liquid cooks down and the cabbage has all but disappeared into the meat, 10 to 15 minutes. You want it saucy, not soupy.
Pile into hard shells, spoon over nachos, build a taco salad, or bowl it over rice. Avocado alongside is never the wrong call.