Add chili, garlic, ½ cup of water, and vinegar to a food processor. Blend to a pulp. Not too smooth; you’ll still want to see little bits of the chili. 

Transfer the chili mix to a small pot. Add sugar and salt to the pot. Bring to a rolling boil, then let it simmer over low heat for about 5 minutes. Use a heat-resistant silicone spatula to stir the mixture occasionally, and to scrape the bottom and sides of the pot to prevent it from burning. 

In a small bowl, dissolve cornstarch in the remaining ¼ cup water.

Bring the sauce mixture up to a rolling boil again, then add the cornstarch slurry to the pot. Stir for another minute.

Allow the chili sauce to cool before transferring it into a jar.

Enjoy!