Trim any surface fat from the ribs. Rub all surfaces of the meat generously with salt and pepper. Put the ribs into a large baking dish that fits them all in a single layer. Drizzle the vinegar over the ribs and turn them over so they have vinegar on both sides. Let the ribs marinate, turning them occasionally at room temperature for up to 1 hour or in the refrigerator for up to 4 hours. (This longer marinating time may make the surface of the ribs turns grayish-white in spots. That is fine and the discoloration will disappear when they are grilled.)
Heat a gas grill to medium-high or build a strong charcoal fire.
Grill the ribs, turning them once, until well browned, even charred here and there, about 6 minutes per side. The ribs should be just a touch rarer than medium-anything less and they will be very chewy. Let them rest 4 to 5 minutes before serving.
Pull the husks from the tomatillos and wash them under cool water until they no longer feel sticky. Cut them into quarters and put them into the work bowl of a food processor. Add the onion and garlic and process until smooth. Add the cilantro, jalapeno and lime juice and process until the jalapeno is finely chopped.
Scrape the mixture into a small saucepan. Season lightly with salt and bring to a boil over medium heat. Cook, stirring occasionally, until most of the liquid is boiled off and the salsa looks relish-y, about 15 minutes. Cool before using. The sauce can be refrigerated for up to 1 week. If refrigerated, you may want to add a little salt and/or lime juice to the salsa before serving.
This is a standard Mexican salsa that you find everywhere in Mexico. Tomatillos have a natural acidic and fresh note that gives them a little sparkle. (They keep that sparkle even after they're cooked.) Tomatillo salsa is a natural with the flavors of grilled meat, but it is a great do-ahead, have-on-hand salsa to freshen up anything off the grill or out of a skillet.