Place meat, bay leaf and salt into a pot. Cover with water and then set heat to low and simmer until meat will be very tender. Make sure meat is always covered with water and you'll need 1 ½ cups of cooking water.
Remove meat from the pan and shredded it. Set aside.
Clean the chilies and place them on a bowl, pour over hot water to cover them and soak for 10 minutes.
Transfer chilies to a blender, add garlic, bay leaf, oregano, cumin, a bit of salt and peppercorns.
Pour in the vinegar and 1 ½ cup of cooking water. Blend for a couple of minutes or until you’ll have a smooth sauce.
In a medium pan melt lard over medium heat. Add shredded pork and fry for about 5 minutes while stirring constantly.
Pour in the chili sauce, mix well and let it simmer, uncovered, for 10 minutes or until you’ll see there’s almost not liquid left.
Adjust with salt if needed and turn off the heat. Serve with warm tortillas.
Allow the meat to cook until almost falling apart. This is the key to shred it with the minimum effort and to get the traditional texture of chilorio.
The right texture of this dish is almost dry, so allow the sauce to evaporate the liquid very well.
You can replace the chilies with 1 small red bell pepper and 1/2 cup of smoked paprika. Boil the pepper until soft and blend it with paprika and spices as the recipe calls.