Peel and remove seeds from pumpkin then cut into cubes.
Heat canola oil in a saucepan. Sweat the onion until soft. Add the grated ginger and cumin powder. Fry until aromatic for about 1-2 minutes.
Add pumpkin and sweet potatoes. Stir and cook for 2-3 minutes. Pour in stock and bring to boil. Reduce the heat and let simmer for 15 minutes or until both pumpkin and sweet potatoes are tender. Remove saucepan from the fire and leave aside to cool slightly.
Transfer the mixture to a food processor. Blend until mixture is smooth. Adjust with seasoning to taste. Warm up the soup again before serving.