1. Heat oven to 350ºF. Place ribs on aluminum foil-lined shallow baking sheet. Rub both sides with olive oil and sprinkle with salt and pepper.
2. Make sure ribs are meaty-side up on baking sheet. Pour salsa verde over top. Cover pan and bake at 350ºF. for 2 hours until meat falls off bones.
3. Keeping rib rack on the baking sheet, use two forks or hands to shred meat and discard bones. Mix juices on pan in with shredded meat.
4. Sprinkle about 1 ½ tablespoons cheese on one half of each tortilla. Top with pulled pork, 1 tablespoon red onion and another 1 ½ tablespoons cheese. Fold tortillas in half forming a half-moon shape.
5. Melt 1 tablespoon butter in large skillet over medium heat. Place two filled tortillas in skillet and cook approximately 1 to 2 minutes on each side, or until browned and crisp. Repeat with remaining butter and filled tortillas. Cut quesadillas into wedges and serve with cilantro and additional salsa verde, if desired.