SERVINGS: MAKES ABOUT 2 1/2 CUPS
1 pound stemmed fresh chiles (such as jalapeño, serrano, Fresno, or habanero; use one variety or mix and match)
2 tablespoons kosher salt
1 1/2 cups distilled white vinegar
Pulse chiles and kosher salt in a food processor until a coarse purée forms. Transfer to a 1-qt. glass jar, loosely screw on lid, and let stand at room temperature for 12 hours to ferment slightly.
Stir in vinegar and loosely screw on lid. Let chile mixture stand at room temperature for at least 1 day and up to 7 days. (Taste it daily; the longer it sits, the deeper the flavor becomes.)
Purée mixture in a food processor or blender until smooth, about 1 minute. Place a fine-mesh sieve inside a funnel. Strain mixture through sieve into a clean glass bottle. (Hot sauce will become thinner and may separate after you strain it; shake vigorously before each use.)
Do Ahead: Can be made up to 4 months ahead. Keep refrigerated.
Recipe by The Bon Appétit Test Kitchen