Whisk corn starch into 2 TBS water to make a slurry. Set aside
Add chilis, garlic, sugar, 3/4 cup water, and salt to a blender. Puree.
Pour into small sauce pan, and heat over medium high heat. Bring to a boil, stirring often as sauces with high sugar content can boil over quickly. Cook for 5-6 minutes or until reduced by 1/3
Pour in slurry, then bring back to a boil while whisking. Reduce heat and simmer for 1-2 minutes. Remove from heat and pour into non-reactive container. Will keep in fridge for up to a week.