01 - Strain fresh watermelon juice through a fine mesh sieve to eliminate all pulp and seed debris, ensuring a smooth liquid base.
02 - In a medium saucepan, whisk together granulated sugar and cornstarch until thoroughly blended and no lumps remain.
03 - Gradually pour watermelon juice into the sugar-cornstarch mixture while whisking continuously to prevent clumping and achieve a uniform consistency.
04 - Stir in fresh lemon zest and vanilla extract, ensuring even distribution throughout the mixture.
05 - Place saucepan over medium heat, stirring constantly to prevent scorching. Continue cooking for 8 to 10 minutes until the mixture reaches a soft, velvety pudding consistency that coats the back of a spoon.
06 - Remove from heat source. If desired for traditional presentation, gently fold mini dark chocolate chips into the warm pudding.
07 - Distribute pudding evenly among serving glasses or molds. Allow to cool completely at room temperature, then refrigerate for a minimum of 3 hours until fully set and firm.
08 - Immediately before serving, sprinkle chopped pistachios over the surface. Optionally enhance with dried rose petals and additional dark chocolate chips for visual appeal.