Season the duck leg with sea salt and black pepper and place in a 5 x 30cm high sided roasting tray. Roast for 1½ hours, or until tender and cooked through.
Transfer the duck to a plate and leave to cool slightly. (At this point you can carefully pour the duck fat from the tray into a clean jar and keep in the fridge for roasting potatoes.)
Place the tray on a medium-high heat, then add 300ml of water and a splash of red wine vinegar. Bring to a simmer, scraping all the lovely sticky bits from the bottom of the pan, and stir through 1 tablespoon of hoisin sauce. Cook the noodles according to the packet instructions, then use tongs to transfer them to the tray and mix well, so they soak up all the lovely juices.
Once the duck is cool enough to handle, shred it from the bone and separate the skin. Add the skin to a dry frying pan on a medium-high heat and fry for 3 to 5 minutes, or until crisp, then set aside. Pop the pan back on the heat and add the shredded duck meat for 2 minutes, then add the remaining hoisin sauce. Cook for 2 further minutes, until crispy and sticky.
Meanwhile, pick the leaves from the herbs, and slice the cucumber, spring onions and sugar snap peas.
Divide the noodles between serving bowls, pouring over any remaining juices. Top with the hoisin duck and crispy skin, with the herbs and crunchy veg alongside and tuck in!