Begin by toasting the guajillo and ancho chilies in a dry skillet over medium heat for about 2-3 minutes, until they become fragrant. This step unlocks the depth of flavor that makes birria so special.
Add the toasted chilies to a bowl and cover with hot water. Let them soak for about 10 minutes until they become soft.
Meanwhile, heat the vegetable oil in a large pot over medium-high heat. Season the beef chunks with salt and pepper, and sear them in the pot, working in batches if necessary, until browned on all sides.
Remove the beef and set aside. In the same pot, add the chopped onion and garlic, sautéing until they are soft and translucent.
Drain the chilies and add them to a blender along with the sautéed onion and garlic, and a cup of beef broth. Blend until you have a smooth paste.
Return the beef to the pot, pour in the chili paste, and add the remaining beef broth, bay leaves, cumin, and oregano. Stir to combine.
Bring the mixture to a gentle boil, then reduce the heat to low. Cover and let it simmer for 2-3 hours, or until the beef is fall-apart tender. Stir occasionally to prevent sticking.
Once the beef is tender, remove it from the pot and shred using two forks. Return the shredded beef to the pot and simmer for another 10 minutes to absorb the flavors.
To assemble the bowls, start with a base of cooked rice or quinoa, then layer with black beans, corn, and the shredded birria beef. Garnish with cilantro and serve with lime wedges and your choice of toppings.
