Break or cut vermicelli noodles in half or into smaller pieces (so they are thin enough to shallow fry). Add enough oil to a medium saucepan to come 2-3cm up the side of the pan. Heat over medium-high heat. To test when the oil is ready, a piece of the vermicelli will sizzle and expand as soon as it hits the oil. In 2 batches, add the noodles and cook for 10 seconds each side or until they are crisp and have expanded. Transfer to a plate lined with paper towel to drain.
Heat extra oil in a large frying pan over medium heat. Add onion and cook, stirring, for 3-4 minutes or until soft. Add ginger, garlic and lemongrass, and cook, stirring, for 1 minute or until aromatic. Increase heat to medium-high. Add chicken mince and cook, stirring and breaking up the mince with a wooden spoon, for 3-4 minutes until cooked through.
Stir cornflour into the mince mixture. Add soy, vinegar, 2 tbsp fish sauce and honey. Season with freshly cracked black pepper and stir in water. Cook, stirring, for 2 minutes or until reduced and sticky. Remove pan from heat and keep warm.
Place red onion, cucumber and chilli in a bowl. Drizzle over remaining 1 tbsp fish sauce and lime juice. Toss to combine. Add coriander and mint and toss to combine. Break noodles into smaller pieces and arrange on a platter. Top with the salad mixture and mince mixture. Sprinkle with chopped peanuts and drizzle over some of the dressing from the salad, to serve.
