Rub seasoning liberally into the meat so it is well coated.
Heat up a large skillet (with sides and a top) to medium-high.
Add some Avocado oil or rendered pork fat
When pan smokes, add 4 pieces of meat to pan and sear until well browned on all sides.
Remove beef from pan, turn down to medium heat and saute onions until soft, scraping up all the brown bits off of the bottom of the pan. Add jalapenos and cook for another minute.
Add beef stock and canned tomatoes, breaking them up with a wooden spoon.
Add beef back to skillet and cover, turning heat down to medium-low. You want the tomatoes at a very slow simmer.
Simmer for about 1 ½ hours or until beef just falls apart.
Shred the beef incorporating the onions and tomatoes and you are ready to eat!