Remove the skin and seeds from the old pumpkin and cut it into bite-sized pieces.
Slice the onion thinly.
Add olive oil to a pot and sauté the onion.
Add the pumpkin and sauté together.
Add water and salt, then bring to a boil.
When the pumpkin is tender, blend smoothly with a hand blender.
Adjust the consistency and seasoning to taste with a spoon.