Birria de Res Tacos (Beef Birria Tacos)

Gather all ingredients. Preheat the oven to 325 degrees F (165 degrees C).

Fill a pot with water; bring to a boil. Add guajillo, arbol, and ancho chile peppers; boil for 5 minutes.

Off heat, allow peppers to soak until cool. Drain; reserve ¼ cup cooking liquid.

Meanwhile, rinse beef; pat dry with paper towels. Cut beef into chunks if desired; season with salt and black pepper.

Heat oil in a Dutch oven over medium-high heat. Add beef; cook until browned on all sides, about 10 minutes. Remove from the heat.

While the beef is searing, line a heavy cast-iron grill pan or griddle with aluminum foil; place over high heat. Arrange tomatoes in a single layer on foil; grill until tomato skins burned on all sides and begins to peel, 3 to 5 minutes.

Place cooled chile peppers into a blender; add charred tomatoes, vinegar, garlic, 2 teaspoons black pepper, cloves, cinnamon, cumin, thyme, marjoram, oregano, and salt. Pour in reserved ¼ cup cooking liquid; blend until smooth.

Strain chile sauce through a mesh strainer; pour over browned beef in the Dutch oven, turning until completely covered with sauce. Cover the Dutch oven with a lid.

Bake in the preheated oven, basting beef every 45 minutes with sauce, until birria begins to fall apart, 3 to 4 hours. Remove the lid; bake, uncovered, until birria is crispy on top, about 20 minutes more. Remove from oven, cover with 2 layers of aluminum foil, and allow to rest in a warm area for 10 minutes.

Transfer beef to a cutting board; strain off any fat from sauce. Shred beef with two forks; return it to the pot and stir with sauce to coat.

Fill each tortilla with birria; top with Mexican cheese, chopped onion, and cilantro. Warm tortillas on a griddle, flipping until both sides crispy and cheese is melted.

Serve with extra sauce on the side for dipping.