Cut top off the chili pepper and finely chop. Mince garlic. Add water, rice vinegar, sugar, and chopped chilies to a frying pan over medium heat. Stir until the sugar dissolves and let boil for approx. 1 min.
In a small bowl, combine cornstarch with equal amount of water to make a slurry. Add minced garlic to frying pan and stir to combine. Add slurry and let simmer for approx. 15 min. or until thickened, stirring often. Allow to cool, then enjoy with gyoza, spring rolls, or samosas!