Season the brisket and short rib with the salt and blot the cubes dry.
Heat the oil in a Dutch oven over medium-high heat and brown the beef in 3 batches for 5 minutes per batch.
Return all the beef and stir in the ancho powder, cumin, garlic powder and tomato paste for 1 minute.
Add the broth and Worcestershire and simmer partly covered for 2 1/4 hours until both cuts reach at least 145°F and are fork-tender.
Whisk the masa harina with the warm water, stir it in, and simmer uncovered for 15 minutes until the gravy looks glossy.