Remove the skin and seeds from the pumpkin, then cut it into small pieces.
Chop the onion.
Heat olive oil in a pot and sauté the onion.
Add the pumpkin and stir-fry together.
Pour in water or milk and let it simmer until the pumpkin is cooked.
Blend until smooth with a hand blender.
Season with salt and pepper to taste.
Bring it to a boil once more to finish.