Begin by poaching the plums. Place the water and sugar in a saucepan over a low heat and stir until the sugar is dissolved. Bring to the boil and reduce to a simmer and add the cardamon pods, vanilla seeds and plums and poach for 10 minutes, or until the plums are softened and the skin starts peeling off. Remove the plums and leave the syrup to reduce for 15 to 20 minutes. Set aside to cool.
In a small bowl add the 2 tbs of the milk with the cornflour (cornstarch) and mix to combine. In a separate large bowl whisk the cream cheese until smooth.
In a medium saucepan combine the milk, sugar, cream and glucose syrup (light corn starch) and bring to a rolling boil over a medium high heat. Boil for 4 minutes before removing from the heat. Add the green Earl Grey tea and leave to steep for 10 minutes.
Fill the sink with cold water and ice.
Strain the mixture through a fine mesh sieve and press the tea leaves to extract all the liquid. Return the mixture to the saucepan and gradually whisk in the cornflour mixture. Return the mixture to a medium high heat and bring to a boil and cook, stirring, until the mixture thickens slightly. Remove from the heat and gradually pour the mixture into the cream cheese, whisking until smooth. Place the mixture into the prepared sink and leave to 30 minutes to cool.
Meanwhile, remove the stones from the plums (and the skins too if you prefer) and place the plums into a food processor and puree until smooth. Add 1 tbs of the poaching liquid, and puree to combine.
Churn the ice cream according to your manufacturers instructions, and when the ice cream is almost ready add 2 tbs of the plum puree to the machine and churn for a minute or two. Remove the mixture from the machine and layer ⅓ of the mixture into a freezer-safe container and drizzle with 1 tbs of the plum mixture. Repeat with remaining ice cream. Place a sheet of baking paper over the top of the ice cream and seal and freeze for 4 hours or until firm.