Wash the sweet pumpkin thoroughly, remove the seeds, and cut it into bite-sized pieces.
Chop the onion.
Heat olive oil in a pot and sauté the onion.
Add the sweet pumpkin and stir-fry together.
Pour in vegetable stock (or water) and boil until the pumpkin becomes tender.
Turn off the heat and allow it to cool, then blend until smooth.
Transfer back to the pot and season with salt and pepper.
If needed, add soy milk (or regular milk) and bring to a simmer one more time.