Preheat the oven to 210 degrees. Peel the squash, remove the seeds, and cut the flesh into large chunks. Toss them with a tablespoon of olive oil, the cumin, salt, and pepper, and roast for twenty-five minutes until the edges turn dark. Roasting instead of boiling makes all the difference here: the sugars in the pumpkin caramelize, giving the soup a depth you can never achieve with boiled pumpkin, no matter how many spices you add.
Meanwhile, finely chop the onion and mince the garlic and ginger as finely as possible. Heat the remaining olive oil in a large pot and sauté the onion over medium heat for eight minutes until soft and sweet. Add the garlic, ginger, coriander powder, and turmeric, and stir for a minute until fragrant.
Add the roasted pumpkin, pour in the stock and three-quarters of the coconut milk, and let it simmer gently for ten minutes. Puree the soup with a hand blender until velvety smooth and season to taste with salt and lime juice.
Dry-toast the pumpkin seeds in a frying pan until they start to pop.
Pour the soup into a bowl, swirl the remaining coconut milk through it in ribbons, and crumble the feta on top. Finish with the pumpkin seeds, plenty of coriander, and black pepper.