Carne con Chile Burritos

6 pounds pork or beef brisket cut into large pieces
2 garlic cloves
1/4 of a large white onion
3 bay leaves
5 Roma tomatoes
Kosher or sea salt to taste
15 chiltepin chiles
3 to 4 chiles de arbol stemmed, seeded and rinsed
3 cascabel chiles stemmed, seeded and rinsed
3 pasilla chiles stemmed, seeded and rinsed
2 dried morita or chipotle chiles stemmed, seeded and rinsed
4 ounces California chiles, chile de sarta, or Colorado
chiles stemmed, seeded and rinsed
1/2 cup lard or vegetable shortening
1/4 cup all-purpose flour
10 large flour tortillas

Place the meat, garlic, onion, bay leaves, tomatoes, and salt in a large, thick
saucepan and cover with water by about an inch. Set over medium-high heat, bring to a boil, then reduce to a simmer and cook until the meat is completely cooked through and tender, about 2 to 3 hours. Remove the meat from the saucepan and chop into small, bite-sized pieces. Reserve the cooking liquid, discarding the bay leaves.
To make the red sauce, put all the chiles in a medium saucepan. Cover them with water and simmer over medium-high heat until they´ve rehydrated and plumped up, about 10 minutes. Once they´re soft and rehydrated, transfer to a blender along with the tomato, garlic and onion from cooking the meat, as well as 1 cup of the reserved meat cooking liquid. Puree until smooth and strain through a fine-mesh sieve or strainer into the remaining cooking liquid from the meat. Stir to combine.
Melt the lard or vegetable oil in a dutch oven or a large pan over medium heat. Once it´s hot, whisk in the flour and cook until it starts to smell toasty and has a sandy consistency. Add the red sauce, mix well with the whisk, and let it simmer for a few minutes until it thickens to a consistency that will coat the back of a spoon. Turn off heat. Add the chopped, cooked meat. Mix well to completely cover the meat with the sauce.
Spoon a couple of tablespoons of the meat with sauce onto large, flour tortillas and roll them to make burritos.