Add chili flakes, garlic, vinegar, honey, 3/4 c. water, and salt to a small saucepan and bring to a boil over med-high heat. Boil for a minute at medium heat, stirring constantly.
Mix the potato starch with the remaining water and add to the sauce, stirring over medium heat until thickened - about another minute or two.
Remove from heat, cool thoroughly and transfer to a container to store in the fridge (the sauce keeps for a couple of weeks, if it lasts that long...). Reused glass dressing bottles or canning jars both work well.
*This amount produces a fairly spicy sauce initially, that mellows after a few days. Increase by 1 teaspoon at a time if you'd like to make it spicier.**Using a starch allows us to use a smaller amount of sugar, but still have a syrupy consistency (traditional sweet chili sauce uses only sugar- a lot - cooked down until syrupy)