This is a dry curry. Do not add water or any liquid as it will spoil both the visual appeal and the texture of the dish. Pumpkin cooks quickly so keep an eye on this as it cooks.
Test your pumpkin before buying it by knocking on it. It should have a nice hollow sound to it. Of course, you can't do that if you are buying cut pumpkin which is where the butternut variety comes in handy. Why not grow your own?