Heat the lard in a heavy Dutch oven or large pot and cook the pork until brown on all sides for about 10 minutes, then remove.
In the same pot, cook the onion, garlic and ½ tsp of salt until the onion is tender and beginning to brown.
Add the toasted chiles, oregano, thyme, peppercorns, star anise, clove, and bay leaves, as well as 10 cups of water, and bring to a boil.
Add the pork back in - the liquid should come up about halfway on the sides of the pork - add more water if needed.
Cover, reduce heat to a simmer until the pork is tender and ready for shredding (usually about 2 to 2 and a half hours).
Remove the pork and let it cool, then shred it into pieces for eating.
Take the liquid and all the remaining contents from the pot and blend until smooth in small batches (be careful as the caldo will be very hot).
Wipe the pot out if desired, and return the blended liquid to pot along with the nixtamal and simmer for about 15-20 minutes, until the flavours have melded and the corn is nice and plump.
Add the pork back in and let it cook for another 5 minutes.
Taste for salt and adjust as needed.
Bowl it up and add desired toppings such as chicharrones, avocado, crema, queso fresco, lettuce, cabbage, radish, onion, totopos, oregano, chile de árbol, lime, or other preferred toppings.
