Gather red chilies, garlic, sugar, vinegar, water, and salt
Remove stems from the chilies
Chop the chilies and garlic
Put chilies, garlic, water, vinegar, sugar, and salt into a saucepan
Bring the mixture to a boil
Reduce the heat and simmer until the chilies soften
Stir until the sugar dissolves
Mix cornstarch with a little water if you want a thicker sauce
Add the cornstarch slurry to the saucepan
Cook until the sauce thickens
Remove from heat and let it cool
Pour into a clean jar or bottle
Store in the refrigerator