Toast the cardamom seeds for 1 minute and then crush them.
Peel the pineapple, disscard core and chop flesh into small chunks, save all the juice.
Put juice, vinegar and spices into a pan and bring to the boil then lower the heat and simmer for 5 minutes.
Add the pineapple chunks and simmer for a further 20 minutes.
Add the sugar and bring to the boil then back to a simmer again.
Cook until it has thickened and you can drag a wooden spoon through the base and leave a clear trail on the pan.
Ladle carefully into sterilised jars and pop on the lids.
Set aside for 1 month before using to allow the flavours to develop and merge.