In a large slow cooker place pork, water, onion, garlic and 1½ teaspoons salt. Slow cook on high for about 4–5 hours, or until meat is very tender. Remove meat from broth and allow both meat and broth to cool (skim off the fat if you wish). Shred and chop the meat, discarding the fat. Strain the broth and reserve.
Remove seeds and rinse guajillo peppers; do the same with the ancho peppers. Place both peppers in large pot and boil until tender. Place softened peppers in high-powered blender with 1 peeled head of garlic, 2 tablespoons of comino, salt to taste, 4 cups of broth; blend well.
In a large saucepan or skillet, heat the red sauce from blender and add meat; simmer, covered, for 10 minutes. In the meantime, soak corn husks in warm water for at least 30–45 minutes; rinse to remove any corn silk and drain well.
To assemble each tamale, spread 2 tablespoons of the masa mixture on the center of the corn husk. (Place masa on the smooth side of the husk, each husk should be 6–8 inches wide. If it is too large, tear a strip from the side.)
Place 1½ tablespoon of meat and sauce mixture in the middle of the masa. Fold in sides of husk and fold up the bottom. Place a bowl or a foil ball in the center of a steamer basket placed in a large pot. Lean the tamales in the basket, open side up. Add remaining broth to boil and reduce heat. Cover and steam 45–60 minutes, adding water when necessary.
There are many versions of traditional tamales. This is my version. When tamales are cooked, place a few on a plate or tray and let them cool for 5 minutes. Then … enjoy!