1. Put the tomato, sugar, and vinegar in a skillet.
2. Until the sugar dissolves, stir.
3. In 40 milliliters of cold water, dissolve the cornstarch.
4. Add the sriracha and cornstarch mixture with water to the pan once there is no longer any visible sugar.
5. Stir continuously for a few seconds or until a streak appears at the bottom of the pan.
6. Take off the heat.