Barbecued pork: Preheat oven to 350 degrees and line a shallow baking pan with foil. In a small bowl whisk together hoisin sauce, ketchup, soy sauce, garlic, and sugar. Put pork tenderloin in baking pan and coat with hoisin mixture. Roast pork in middle of oven 35 to 40 minutes, or until a meat thermometer inserted in center registers 160 degrees. Cool pork completely in baking pan.
Make garlic sauce while pork is cooling: In a small bowl stir together sauce ingredients until sugar is dissolved. Transfer pork to a cutting board and with a knife held at a 45 degree angle cut meat across grain into thin slices. Arrange pork, overlapping slices slightly, over noodles. Spoon garlic sauce over pork and sprinkle pork with coriander.