How to Make It
In a medium saucepan, bring the water, chiles, onion, garlic and 1 teaspoon salt to a boil. Reduce the heat and simmer until the vegetables are very tender, 15 to 20 minutes.
Let the mixture cool to warm, then puree in a blender with the vinegar. Season with salt to taste, then place in a pint jar. Refrigerate for at least 3 weeks for optimal flavor.