01 - Strain fresh watermelon juice through a fine mesh sieve to remove all pulp and seeds, ensuring a smooth liquid base.
02 - In a medium saucepan, whisk together granulated sugar and cornstarch until thoroughly 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 evenly distributed throughout the mixture.
05 - Place saucepan over medium heat, stirring constantly for 8-10 minutes until mixture reaches a soft pudding consistency and thickens noticeably.
06 - Remove from heat and gently fold in dark chocolate chips if using for traditional texture and appearance.
07 - Pour pudding into individual 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 each portion along with dried rose petals and additional chocolate chips if desired.