Place your dried chiles in a bowl and pour the boiling water over. Let the chiles soak. Oftentimes, I have had to put a lid or a plate on them to get them to stay submerged. Let cool until handleable, discard the stems, and retain your soaking water.
Scrape the soft chile pulp from the skins and mash - or - puree the soft chiles with a little soaking water in a blender and then strain. Reserve.
Using a heavy skillet, fry the garlic in the lard. If you like cumin, add the cumin at this time and fry for a minute until fragrant. Add the chile pulp and fry for a few minutes until you notice a darkening of color and thickening of texture.
Add the tomato sauce, any reserved chile soaking liquid and the oregano and simmer on low for ten minutes -or longer if you would like a thicker consistency. When done, add the 1/2 t. of vinegar and add salt to taste.