Preheat your oven to 275°F (135°C). Pat the Beef Shank dry and season generously with Salt and freshly ground Black Pepper.
In a heavy skillet or Dutch oven, heat a few tablespoons of Olive Oil over medium-high heat and brown the shanks on all sides to build flavor—work in batches if needed. Transfer the browned shank to your braising pot (a traditional tangia or a small Dutch oven).
Mince the Garlic and finely chop the flesh of the Preserved Lemon, discarding or reserving the very bitter pith. In a bowl combine the garlic, preserved lemon, and Ground Cumin. Add the mixture to the braising pot, rubbing it onto and around the meat.
Toast the Saffron Threads briefly between your fingers, then bloom them in a tablespoon of hot Water for a few minutes to draw out their color and aroma; pour the saffron and its soaking liquid into the pot.
Add a couple of tablespoons of Smen and an additional splash of Olive Oil into the pot with the meat. Pour in enough Water to come about two-thirds up the side of the shank—there should be liquid but the meat should not be completely submerged.
Bring the pot to a gentle simmer on the stovetop, then cover tightly and transfer to the preheated oven. Cook low and slow for 3 to 4 hours, or until the meat is fall-apart tender and the sauce has concentrated and become glossy.
Check once or twice during cooking: skim any excess fat if desired and add a little more Water if the liquid reduces too far. Taste near the end and adjust seasoning with more Salt or Black Pepper as needed.
When the shank is fork-tender, remove from the oven. Let it rest for 10 minutes in the pot so the flavors settle and the sauce thickens slightly.
Serve the tangia family-style, spooning the fragrant sauce over the shank and tearing pieces off with warm Moroccan Bread to soak up every drop.
