FOR LAMB: Mix oil, 2 tablespoons hoisin, wine, garlic, ginger and red pepper in medium saucepan. Stir over low heat until warm, about 4 minutes. Cool. Place lamb in glass baking dish. Pour marinade over. Cover; chill at least 4 hours or overnight.
Preheat oven to 375°F. Drain lamb; pat dry. Heat heavy large skillet over high heat. Add 1 lamb rack; sear on all sides, about 6 minutes. Transfer to baking pan. Repeat with remaining rack. Cool 15 minutes. Mix chili sauce and 8 tablespoons hoisin in small bowl. Brush over lamb. Press nuts onto lamb, coating completely. Bake until meat thermometer registers 130°F for medium-rare, about 20 minutes. Transfer to platter. Tent with foil.
MEANWHILE, PREPARE SAUCE: Boil stock and wine in large skillet until reduced 3/4 cup, about 15 minutes. Add chili sauce and hoisin; boil until reduced to 1/2 cup, about 4 minutes. Remove from heat. Add butter; whisk just until melted.
Cut lamb between ribs into double chops. Serve with sauce.