Preheat your oven to 300°F with one rack in the middle setting and another on the topmost setting right under the broiler.
In a small sauce pot, combine all of the ingredients for the sauce and whisk well. If making applesauce from scratch, peel and puree apples before adding to the pot.
Remove the ribs from their packaging and pat dry on both sides. Cut each rack in half so that you have four sections of ribs. Flip the racks over so the bone side is facing up. Use a sharp knife to make two slashes down the ribs, cutting across the bones. Use just enough pressure to slice the thin membrane so it doesn't tighten up in the oven.
Line a sheet pan with aluminum foil, wrapping the foil around the edges so that it's secure.
Working with one section of ribs at a time, place the ribs on top of a fresh sheet of aluminum foil and generously salt and pepper each side of the ribs. Then brush both sides of the ribs generously with the glaze.
With the ribs horizontal to you on the counter (meaning, the long side of the ribs is facing you) fold the top and bottom edges of the foil up over the ribs so they overlap. Then roll or fold the left and right edges of the foil in to seal the packet tightly. Repeat with the rest of the ribs until you have four foil packets.
Arrange the foil packets on the sheet pan and place in the oven for 3 hours.
During the last 30 minutes of cooking, place the pot with the glaze on the stove over a low-medium heat and reduce it to thicken and to kill off any harmful bacteria from when you brushed the glaze onto the ribs. Make sure you wash the brush you used, too. Keep an eye on the glaze as it reduces, stirring occasionally and adjusting the heat as needed so that it doesn't burn.
When the ribs are done, carefully remove them from their foil packets. There will be some accumulated juices in the packets that are very hot so you may want to do this over the sink. The ribs will be fully cooked and very tender but also kind of grey and ugly looking. That's all about to change.
Turn on your oven's broiler. While you wait for it to heat up, arrange the ribs back on the foil-lined sheet pan. Brush both sides of the ribs with the reduced glaze. Be generous here — use up all the remaining glaze.
Once the broiler is hot, slide the sheet pan onto the top rack of the oven for about 5-6 minutes, rotating the sheet pan halfway through. The ribs are already fully cooked, so this is just about getting them blackened and a little charred. You can leave them in for up to 8 or even 10 minutes to achieve your desired level of char.
Remove the ribs from the oven, slice and serve!