Chop pumpkin: Halve the pumpkin or squash and peel it (Hokkaido pumpkin doesn’t need peeling, but anything else does). Slice it thickly and cut the slices into even cubes.
Chop vegetables: Peel the carrots and cut them into slightly smaller cubes than the pumpkin cubes. Peel and chop the onion, garlic, and ginger, and keep them separated.
Saute: Melt the butter in a large pot. Cook the onion on medium heat for about 3 minutes or until translucent. Add the garlic, ginger, cumin, coriander, a few gratings of nutmeg, red pepper flakes, salt, and pepper, and stir for 30 seconds.
Add pumpkin and carrot cubes and stir for 2-3 minutes.
Simmer: Add stock, cover, bring to a boil, and simmer for 15-20 minutes or until soft.
Blend the soup with an immersion blender (Notes 3,4).
Add coconut milk, soy sauce, and one tablespoon of lemon juice. Stir well and reheat the soup.
Adjust the taste with more lemon juice, salt, and pepper.
Roast the pepitas (if not already roasted) in a dry pan for 2-3 minutes or until golden and fragrant. Shake the pan frequently, and don’t let them unattended; they will burn quickly. Transfer them to a plate until ready to serve.
Sprinkle the soup with the roasted seeds and chopped parsley or cilantro before serving. You can swirl a little coconut milk into each bowl if you like.