Step 1In the bowl of a food processor, pulse together the chiles, garlic, vinegar, salt and sugar to form a coarse paste.
Step 2Transfer the mixture to a non-reactive saucepan and simmer, stirring occasionally, until the aroma softens or mellows a bit, about 5 minutes. Remove from heat.
Step 3Blend the sauce again to form a smooth paste, thinning as desired with water.
Step 4Strain the sauce, pressing the solids through a fine mesh strainer with a rubber spatula or wooden spoon. Taste the sauce, and tweak the flavors as desired with additional salt, sugar or vinegar. Remove the sauce to a glass jar or bottle and cool completely. Refrigerate until needed.