Preheat the oven to 180ºC/350ºF/gas 4. Wash the duck and pat it dry, inside and out, with kitchen paper, then rub it all over, inside as well, with salt and pepper. Place it in a tray and roast in the preheated oven for around 2 hours, turning it every now and then. Halfway through, you’ll probably need to drain away a lot of the fat from the bird. Don't throw it away, though! Sieve it and keep the fat (but no meat juices) in a jar in the fridge for a couple of months and use it to roast potatoes.
In a pestle and mortar or a Flavour Shaker, bash up the dried chillies and coriander seeds and add the ground cinnamon and a good pinch of salt and pepper. Scoop the seeds out of your squash and put them to one side. Cut the squash into wedges, place them in a roasting tray, and drizzle over enough olive oil just to coat. Sprinkle over the ground spices and give the squash a good toss, spreading the pieces out in one layer. Once the duck has been in the oven for 1 hour and 15 minutes, add the tray of squash to the oven and roast for about 45 minutes.
Meanwhile, rinse the squash seeds after removing any fibres. Season with salt and pepper and drizzle with olive oil. Toast them in a dry frying pan until they’re golden and crisp, and put aside. To make the dressing, put the lime juice and zest into a bowl and add the same amount of extra virgin olive oil, plus the sesame oil and the soy sauce. Stir in the sugar, chilli, garlic, the green spring onion ends and coriander stalks. Taste and adjust the sweet-and-sourness and the seasoning. You want it to be a little limey, to contrast with the rich duck.
After 2 hours, if the duck is nice and crispy, and the squash soft and sticky, take both trays out of the oven. If they need more time, leave them in until perfectly done. Using two forks, shred the duck meat off the bone and put into a large bowl. While the duck and squash are still warm, toss with the toasted seeds, half the coriander leaves, half the mint and half the white spring onion slices. Pour on the dressing and toss together. Serve sprinkled with the rest of the coriander, mint and white spring onion slices.