Place beef and garlic in a large pot. Cover with cold water and bring to a boil over high heat. As soon as water boils, reduce heat to a simmer and cover pot. Let simmer for 3 1/2 hours, until beef is tender and shreds easily. When beef is done, remove from pot, reserving 5 cups cooking liquid and discarding garlic. Allow meat to cool slightly, and shred finely with forks.
Meanwhile, place corn husks in a large container and cover with warm water. Allow to soak for 3 hours, until soft and pliable. May need to weight down with an inverted plate and a heavy can.
Toast ancho chiles in a cast iron skillet, making sure not to burn them. Allow to cool and then remove stems and seeds. Crumble and grind in a clean coffee grinder or with a mortar and pestle.
Heat oil in a large skillet. Mix in flour and allow to brown slightly. Pour in 1 cup beef broth and stir until smooth. Mix in ground chiles, cumin seeds, ground cumin, minced garlic, oregano, red pepper flakes, vinegar and salt. Stir shredded beef into skillet and cover. Let simmer 45 minutes.
Place lard and salt in a large mixing bowl. Whip with an electric mixer on high speed until fluffy. Add masa harina and beat at low speed until well mixed. Pour in reserved cooking liquid a little at a time until mixture is the consistency of soft cookie dough.
Drain water from corn husks. One at a time, flatten out each husk, with the narrow end facing you, and spread approximately 2 tablespoons masa mixture onto the top 2/3 of the husk. Spread about 1 tablespoon of meat mixture down the middle of the masa. Roll up the corn husk starting at one of the long sides. Fold the narrow end of the husk onto the rolled tamale and tie with a piece of butchers' twine.
Place tamales in a steamer basket. Steam over boiling water for approximately one hour, until masa is firm and holds its shape. Make sure steamer does not run out of water. Serve immediately, allowing each person to unwrap their own tamales. Allow any leftovers (still in husks) to cool, uncovered, in the refrigerator.