To prepare fire, mound and ignite 50 charcoal briquets
When coals are heavily spotted with gray ash, spread to make an even layer.
Set tomatoes and chiles on a lightly greased grill 4 to 6 inches above prepared coals.
Cook, turning as needed, until chiles are charred on all sides (7 to 10 minutes) and tomatoes are hot and streaked with brown
Using long tongs, mound hot charcoal for indirect cooking , adding 5 fresh briquets to each side.
To make the salsa, chop tomatoes and chiles; discard stems and seeds.
Place chopped tomatoes and chiles and their juices in a bowl.
Stir in vinegar, cilantro, and garlic; season to taste with salt.
Spread some of the salsa evenly over both sides of ribs.
Place ribs, meat side up, on grill directly above drip pan (overlap ribs to fit on grill if necessary).
Cover barbecue and adjust dampers as necessary to maintain an even heat.
Cook, basting occasionally with some of the remaining salsa, until meat near bone is no longer pink; cut to test (1 to l!/4 hours).