Preparation Heat oil in heavy medium saucepan over medium-high heat. Add onion and sugar. Sauté until onion is golden, about 6 minutes. Mix in wine and next 5 ingredients. Cook 1 minute longer. Remove from heat. Cool sauce completely. Place pork in large resealable plastic bag. Pour 1 cup sauce over pork. Seal and refrigerate at least 6 hours or overnight, turning meat occasionally. Cover remaining sauce separately and refrigerate. Prepare barbecue (medium heat). Remove pork from marinade; discard marinade. Grill pork until meat thermometer inserted into center registers 155°F, turning often, about 35 minutes. Meanwhile, boil remaining sauce in heavy medium saucepan until reduced by half, about 5 minutes. Add peaches. Stir until heated through, about 1 minute. Slice pork and arrange on platter. Spoon some sauce over. Top with chives. Pass remaining sauce separately.
Preparation Heat oil in heavy medium saucepan over medium-high heat. Add onion and sugar. Sauté until onion is golden, about 6 minutes. Mix in wine and next 5 ingredients. Cook 1 minute longer. Remove from heat. Cool sauce completely. Place pork in large resealable plastic bag. Pour 1 cup sauce over pork. Seal and refrigerate at least 6 hours or overnight, turning meat occasionally. Cover remaining sauce separately and refrigerate. Prepare barbecue (medium heat). Remove pork from marinade; discard marinade. Grill pork until meat thermometer inserted into center registers 155°F, turning often, about 35 minutes. Meanwhile, boil remaining sauce in heavy medium saucepan until reduced by half, about 5 minutes. Add peaches. Stir until heated through, about 1 minute. Slice pork and arrange on platter. Spoon some sauce over. Top with chives. Pass remaining sauce separately.