Score the ribs by slicing them at 1/4-inch intervals 1 way and then the other across the fatty tops, as if you were setting up a crossword puzzle.
Remove the seeds and stems from the chiles, soak them in hot water for 20 minutes, drain and place them in a blender jar. Add the oregano, garlic, cumin, vinegar, oil and salt. Blend the mixture for 1 minute. (if the mixture is too thick to blend properly, add a little water and continue). Pour the chile sauce over the ribs and marinate, refrigerated for 2 hours.
Cook the ribs at 2 to 2 1/2 feet from mesquite coals for 1 to 2 hours or until they are tender. If your barbecue will not accommodate this distance cook the ribs over very low direct heat, or in a Texas style smoker.