Place the pumpkin cubes in a sieve and sprinkle with salt. Stir and allow at least 30 minutes to extract the water from the pumpkin. Rinse under water.
Chop the onion, the garlic and the ginger. Simmer with the cardamom and the cinnamon in a knob of butter. Add the pumpkin cubes and the remaining ingredients. Bring to the boil and simmer gently until tender. Allow to cool.