Season lamb generously all over with salt and pepper (I use about a teaspoon of salt per pound and 1/4 teaspoon of pepper). Let sit out at room temperature while you prepare the guajillo sauce.

Heat a comal or medium dry frying pan (ideally a cast iron skillet) over medium heat. Place the chiles on the comal and toast, turning frequently until the color has darkened and they are fragrant. Be careful not to burn.

Bring a small saucepan of water to a boil. Remove from the heat and add the toasted chiles. Submerge under the water and let sit until soft, about 15 minutes.

Return the comal to medium-high heat and add the onions and garlic. Char on all sides. The garlic will cook faster so remove it first, careful not to burn or it will become bitter.

Peel the garlic and add to a blender along with the charred onions. Remove the chiles from the water with kitchen tongs and place in the blender along with a ladle full of chile-soaking water. Add the tablespoon cider vinegar, teaspoon oregano, teaspoon cumin, and 2 teaspoons kosher salt. Blend until very smooth.

Heat oven to 300°F.

Heat the 1/4 cup lard in a large, oven-safe Dutch oven over medium high heat. Once shimmering add the seasoned lamb and brown on all sides, about 10 minutes. Remove to a plate.

Add the carrots and celery and season with salt and pepper. Cook until lightly caramelized, about 10 minutes then add the beef broth and scrape up any browned bits from the bottom of the pot.

Add the guajillo sauce and the lamb and bring to a boil.

Cover and transfer to the oven. Braise until the meat easily pulls apart with a fork, about 3-4 hours.

Remove lamb to a baking sheet with kitchen tongs and let cool. Save sauce.

Once lamb is cool enough to handle, shred into bite-sized pieces with your fingers. Discard any fat or gristle. Place lamb in a large bowl. Break the carrots and celery into bite-sized pieces as well and mix in with the lamb. Pour remaining sauce over the lamb and vegetables and stir to combine.

For the tamales

Soak the corn husks: Bring a large pot of water to a boil. Remove from the heat and add corn husks. Submerge them under the water with kitchen tongs. Set aside.

Make the masa: Bring the 10 cups of beef broth to a boil. Place the 6 cups of masa harina in a large heat-proof bowl and pour 6 cups of the broth over the masa harina. Stir until masa is evenly moist. Masa will still be crumbly, we are just rehydrating it at this point, it doesn't need to be super soft. If it is still really dry add another cup of broth. Save the remaining broth for adding later. Cover bowl of masa with plastic wrap to capture the steam in the bowl.

Place 1 cup of lard, 1 tablespoon baking powder and 1 tablespoons salt in the bowl of a stand mixer fitted with a paddle attachment. Beat on high until light and fluffy, about 5 minutes. Turn off the mixer and scrape down the sides of the bowl with a rubber spatula.

Turn mixer back on to medium speed. Start adding the rehydrated masa a handful at a time, letting it whip in before adding the next. You want to really beat the dough and incorporate a lot of air. Keep adding the masa until all the dough is added.

Stop the mixer and feel the dough, it should be light and fluffy like whipped mashed potatoes, maybe even a bit wetter than that. If it is still too dry, add more broth, 1/2 cup at a time until it is almost soupy. It will dry as it sits so it is better to be on the wet side.

Drain corn husks. Remove corn husks to a baking sheet with tongs letting any excess water drip back into the pot. Squeeze corn husks over the pot or the sink to get rid of any water.

Prepare steamer. Fill a tamales steamer with water just until it reaches the rack where the tamales will sit. Use a few of the small or ripped soaked corn husks to line the rack. Cover and bring to a boil over medium-high heat. Once boiling, turn heat to medium and keep covered.

Spread masa. Dry a large corn husk (at least the size of your hand with the fingers together that is free from holes or tears) with a clean kitchen towel. Hold the corn husk with the wide end toward you. Using a large spoon, evenly spread about 1/2 cup masa from the middle of the husk down leaving about 1/2-inch border on the sides.

Fill. Place about 3-4 tablespoons of the lamb filling down the middle.

Fold and roll. Fold one side of masa over the filling until the two edges of the corn husk meet, and holding onto one side of corn husk, pull the other side toward the middle to press the two edges of masa together. Roll up the corn husk and fold the pointy end of the corn husk up over the large end, and place on a clean baking sheet. Repeat with remaining corn husks, masa, and filling. Watch how I roll the tamales in the video below.

Steam tamales. Place tamales vertically, open-side up in the tamale steamer, keeping them snug in the pot so they don’t unravel during cooking. Don't stack the tamales. There needs to be enough space for the steam to circulate otherwise they won't cook evenly. Make sure water is at a steady simmer and producing lots of steam. Cover the top of the tamales with more corn husks then cover tightly with the lid and steam until masa is cooked through and just a tiny bit doughy in the middle, about 45 minutes. Check occasionally and add more water if the pot looks dry.

Let rest. Remove from the pot to a platter and let sit, covered, 5 to 10 minutes before serving to let them finish cooking. Tamales can also be left in the pot (off the heat), covered with a clean towel (and then covered with the steamer lid) for up to an hour before serving. They will stay warm and soft if you want to make them in advance.

Serve! Remove the tamales from the corn husks and serve with salsa verde or your favorite salsa.