Sweet-and-Sour Balsamic-Glazed Spareribs

Preheat the oven to 250°F and place each rack of ribs on a square of aluminum foil. Sprinkle the ribs generously with salt, add a few sprigs of thyme to each, and then wrap well. Place the rib packets on a cookie sheet and bake for 3 to 4 hours, until the ribs are extremely tender. Allow the ribs to cool slightly in their packets before opening.
To make the glaze, combine all of the ingredients in a large pot on medium-low heat. Allow to simmer, stirring every so often, for a few hours, until the sauce is nice and thick. Set aside.
To bring the ribs and glaze together, do the following. Turn on the broiler (if you don't have a broiler, get the oven up to 450°F). Cut the rib racks into individual ribs, place them on a foil-lined cookie sheet or broiler tray, and brush them aggressively with the glaze. Pop them under the broiler and watch them carefully: all that sugar makes them burn very easily! You want the glaze to fuse with the ribs; it takes 3 to 4 minutes. If you're cooking the ribs in the oven, do so just until the glaze begins to bubble, 4 to 5 minutes. Serve the ribs hot with lots of napkins—trust me, you'll need them.