Start by heating the beef tallow or butter in a cast iron pan over high heat. Add the beef shanks and brown them on both sides (about 3 minutes per side).
Pour the broth over the shanks and season with salt and pepper.
Bring to a simmer. Then, if you want to cook on the stovetop, reduce the heat and cover with a lid. Cook on low heat for 3 to 3.5 hours until the meat is tender.
If you want to cook the meat in the oven, after it simmers, put the lid on and bake in the oven for 2 to 2.5 hours until the meat is tender. Optional: shred the meat and serve.