Step 1 Place noodles into a large heatproof bowl. Cover with boiling water. Stand for 5 minutes. Rinse under cold running water. Drain. Set aside.
Step 2 Place pork into a bowl. Add 2 tablespoons hoisin sauce. Combine until pork is coated in sauce. In a separate smaller bowl, combine remaining hoisin sauce with soy sauce. Set aside.
Step 3 Heat a wok or large non-stick frying pan over high heat. Add pork, in batches, stir frying for 2-3 minutes or until cooked through. Transfer to a large bowl. Add noodles, onion, 2 tablespoons shredded mint and sauce. Toss to combine.
Step 4 Divide noodle mixture between lettuce cups. Serve topped with bean sprouts and remaining mint leaves.