Remove the stems and seeds from the chiles.
Cover chiles with boiling chicken stock and let them steam for about 30 minutes until plump and tender.
Put the chiles and soaking liquid into a blender and purée until very smooth.
Cut the pork shoulder into ½” pieces, season with salt and pepper, and brown in a pot with vegetable oil.
Chop garlic and add to the pot along with bay leaves, ground cumin, sage, and oregano. Stir until fragrant.
Add chicken stock and simmer uncovered for about an hour.
Stir in the chile purée and simmer for another 45 minutes until the meat is tender and the sauce is thick.
Season with additional salt and pepper.
