If possible, make this chutney a few days before you want to serve it, to allow the flavors to combine.
Chop the onions and cut the pumpkin into small cubes. Heat the olive oil and fry the onions and the cardamom. Add the remaining ingredients and let the mixture simmer for 20 minutes. Let it cool down and transfer the chutney into sterilized jars. Serve the chutney in jars or a serving bowl.