Cook 1 1/2 pounds prunes in 2 cups of water slowly until prunes are very soft.
Remove prunes from juice and stone.
Mash prunes with a fork and return to the juice.
Add 1 1/2 cups sugar, 1 teaspoon ground cardamom seed and 2 tablespoons lemon juice.
Reheat to the boil and cook for a few minutes or until thick.