In a small saucepan, combine the water, sour plums, and sugar.
Bring the mixture to a boil, then remove it from the heat and allow it to cool completely.
Meanwhile, bring another pot of water to a boil, then turn off the heat. Add the cherry tomatoes and soak them for 1–2 minutes.
Transfer the tomatoes to a bowl and gently peel off their skins.
Place the peeled tomatoes into a large container or bowl.
Pour the cooled sour plum mixture over the tomatoes.
Add the lemon slices.
Pour in the Sprite until the tomatoes are fully submerged.
Cover and refrigerate for at least 3 hours. For the best flavor, chill overnight.
Serve cold and enjoy!
