Combine 1 gallon water and salt in a large stockpot, stirring until salt dissolves. Add pork to brine; refrigerate for 24 hours.
Remove pork from brine; discard brine. Pat pork dry with paper towels.
Preheat oven to 375°.
Combine sugar, vinegar, bourbon, peppercorns, and bay leaf in a small saucepan. Bring to a boil; cook 9 minutes or until reduced to 2/3 cup. Strain mixture through a sieve over a bowl; discard solids. Set aside.
Combine olive oil, ground pepper, and garlic in a small bowl; rub evenly over pork. Top with thyme sprigs. Place pork in a large roasting pan. Bake at 375° for 1 hour and 10 minutes. Brush brown sugar mixture evenly over pork; bake an additional 20 minutes or until thermometer inserted into the thickest portion of pork registers 140° (slightly pink). Place pork on a platter. Cover loosely with foil; let stand 15 minutes before slicing.
Wine note: Brined Pork Loin with Brown Sugar–Bourbon Glaze begs for a wine that's not actually sweet, but seems to be because it's so fruity. Juicy red Zinfandel is that kind of wine. Go for Dutton Goldfield's intense 2007 Zin from the Morelli Lane Vineyard in California's chilly Russian River Valley ($40). Planted by Italian settlers more than 100 years ago, these vines give up bright berry and cherry flavors, plus a spiciness that makes the most of the black peppercorns in the glaze (and, in fact, the rest of this tangy, spicy menu). --Sara Schneider