Remove stems and seeds from dried chiles carefully.
Soak chiles in hot water for 30 minutes.
Blend soaked chiles with soaking liquid until smooth.
Strain mixture through fine mesh to remove skins.
Heat oil in Dutch oven over medium heat.
Season pork cubes with salt and pepper thoroughly.
Brown pork pieces on all sides, about 8 minutes.
Add minced garlic and cook for 1 minute.
Pour chile sauce over browned pork completely.
Add cumin and oregano to the mixture.
Bring to boil, then reduce heat to low.
Cover and simmer for 2.5 to 3 hours.
Stir occasionally to prevent sticking or burning.
Cook until pork shreds easily with fork.