2Cut the Pork shoulder into large, manageable chunks. In a large pot, combine the Pork shoulder, 200g of White onion, 30g of Garlic cloves, and 10g of Salt. Cover the ingredients with water and bring to a boil. Reduce the heat to low, cover, and simmer for 90-120 minutes, or until the Pork shoulder is very tender and easily shreds. Reserve 200g of the pork cooking broth for the sauce and shred the cooked Pork shoulder using two forks.
3While the pork cooks, prepare the chile sauce. Remove the stems and seeds from the Ancho chiles and Guajillo chiles. Lightly toast the chiles in a dry pan over medium heat for about 30 seconds per side, being careful not to burn them. Place the toasted chiles in a bowl and cover with hot water; allow them to rehydrate for 20 minutes.