01 - Strain the watermelon juice through a fine mesh sieve to remove all pulp and seeds, ensuring a smooth liquid base for the pudding.
02 - In a medium saucepan, whisk together the granulated sugar and cornstarch until thoroughly blended and no lumps remain.
03 - Gradually pour the watermelon juice into the saucepan while whisking continuously to create a smooth, lump-free mixture.
04 - Stir in the lemon zest and vanilla extract, ensuring they are evenly distributed throughout the mixture.
05 - Place the saucepan over medium heat, stirring constantly. Continue cooking for 8 to 10 minutes until the mixture reaches a soft pudding consistency and coats the back of a spoon.
06 - Remove from heat and gently fold in the dark chocolate chips, allowing them to soften slightly for the traditional seeded appearance.
07 - Pour the pudding into individual serving glasses or molds. Allow to cool to room temperature, then refrigerate for at least 3 hours until completely set.
08 - Just before serving, sprinkle the surface with finely chopped pistachios, dried rose petals, and additional chocolate chips for decoration and texture contrast.