
In a medium bowl, soak guajillo & pasilla chiles in hot water for about 10 minutes or until they become soft. Reserve ½ cup of this water.
In a blender, add the chiles and the ½ cup of chile water, spices, garlic & vinegar.
Blend well until it forms a paste consistency.
Add the chile paste to the ground beef and mix everything well with a spatula or knead with your hands as if making dough for bread.
Place the beef chorizo over a strainer, then place the strainer over a bowl. Cover with plastic and place in refrigerator for 4 to 6 hours preferably overnight. Note: placing the beef over a strainer, allows for the extra liquid to be released and avoids soggy chorizo. Discard juices.
Allow the mixture to stand refrigerated for at least 6 hours or up to 2 days so the chorizo can ripen. Time allows the spices to infuse their flavors into the ground beef and for the chorizo's overall flavor to develop.
Once the chorizo has cured you can freeze it in smaller portions and use as needed.