01 - Line an 8x8 inch baking pan with parchment paper and lightly grease it to prevent sticking.
02 - In a small saucepan, combine watermelon puree, corn syrup, and lemon juice. Stir until well blended.
03 - Sprinkle gelatin powder evenly over the fruit mixture. Let stand for 5 minutes to allow the gelatin to absorb liquid and soften.
04 - Add granulated sugar to the saucepan. Warm over medium-low heat, stirring constantly until both sugar and gelatin are completely dissolved. Do not allow the mixture to boil.
05 - Pour the hot liquid into the prepared baking pan. Smooth the surface with an offset spatula and let cool at room temperature for 30 minutes.
06 - Transfer pan to refrigerator and chill uncovered for 2 hours or until candy is completely set and firm to the touch.
07 - In a small bowl, whisk together granulated sugar and citric acid powder until evenly combined.
08 - Remove set candy from pan and cut into small squares using a sharp knife. Roll each piece in the sour sugar mixture, ensuring even coating on all sides.
09 - Place finished chews in an airtight container, separating layers with wax paper to prevent sticking. Best consumed within one week.