Recipe Damson Plum Cardamom Jam

Rinse and de-stem plums, then place them in a heavy-bottomed pot with water and cardamom pods. Bring to a boil over medium heat before reducing to a low simmer for 1 1/2 hours uncovered. After cooling, strain the mixture through a colander, squeezing the pulp and skins into a bowl while discarding the pits. Return the plum mixture to the pot with sugar and butter, simmering on low for 4 hours until thick. Verify the set by placing a spoonful on a chilled plate in the refrigerator. Ladle the finished jam into hot, sterile jars, seal with lids, and let cool to room temperature.