Directions

1. Remove the thin, papery membrane from the back of each rack of ribs: Turn a rack meat side down. Insert a sharp implement, such as the tip of a meat thermometer, under the membrane (the best place to start is right next to the first rib bone). Using a dishcloth or pliers to gain a secure grip, pull off the membrane. Repeat with the remaining racks.
2. Place the ribs in a large non-reactive roasting pan. Pour the 1-quart of pineapple juice over them and add the fresh cilantro and 4-8 jalapenos. Let the ribs marinate in the refrigerator, covered, for 2 to 3 hours.
3. Make the glaze: Place the 2 cups pineapple juice, the vinegar, 3 Tbs brown sugar, butter, and 1/2 tsp black pepper in a heavy saucepan over high heat and bring to a boil. Let the glaze boil until syrupy and reduced to about 1 cup, 10 to 15 minutes, stirring occasionally with a wooden spoon. Set the glaze aside.