01 - Pour fresh watermelon juice through a fine mesh sieve to remove all pulp and seeds, ensuring a smooth base for the pudding.
02 - In a medium saucepan, whisk together granulated sugar and cornstarch until evenly blended.
03 - Gradually pour watermelon juice into the saucepan while whisking continuously to prevent lumps from forming.
04 - Stir in lemon zest and vanilla extract until fully incorporated.
05 - Place saucepan over medium heat, stirring constantly. Cook for 8-10 minutes until mixture thickens to a soft pudding consistency.
06 - Remove from heat and gently fold in dark chocolate chips for a traditional seeded appearance, if desired.
07 - Transfer pudding to serving glasses or molds. Allow to cool at room temperature, then refrigerate for at least 3 hours until fully set.
08 - Just before serving, sprinkle chopped pistachios over the top. Add dried rose petals and extra chocolate chips if desired.