How to Make It
In a large saucepan, combine the water with the Lillet, sugar, vanilla bean and cardamom pods. Bring to a boil and cook, stirring, until the sugar is dissolved, about 1 minute. Stir in the plums and simmer over moderate heat until just tender, about 5 minutes.
Using a slotted spoon, transfer the plums to a plate. Boil the poaching liquid over high heat until reduced to 1 1/2 cups, about 12 minutes. Discard the vanilla bean and cardamom pods. Return the plums to the liquid, stirring to coat. Spoon the warm plums and sauce into bowls and serve at once.