Preheat the oven to 200°C. Cover the vermicelli in boiling water and leave for five minutes, then drain, rinse and set aside.
Heat the sesame oil in a medium saucepan and fry the garlic and chilli for one minute. Add the pak choi stems, green beans, soy sauce and lime juice, toss to coat and cook for two minutes.
Remove from the heat and add the pak choi leaves, then toss through the vermicelli, two tablespoons of the spring onions and two tablespoons of the coriander leaves.
In a small bowl, mix together the miso, mirin and ginger, and evenly brush over each of the fillets.
Divide the noodles between two large squares of baking parchment on an oven tray and place the salmon fillets on top. Sprinkle over the sesame seeds, and the remaining spring onions and coriander leaves. Fold the paper up and twist to seal. Cook in the oven for 12–15 minutes until the fish flakes easily when tested with a fork. Once cooked, allow it to cool.
Pack the miso salmon parcels into lunch boxes and store in the fridge overnight. Serve with the avocado, watercress and lime wedges.