Using a toothpick or knife, poke a hole through a few peppers so that the vinegar will penetrate (Optional. This will make your sauce hotter).
Add the chiles, garlic, and salt to the jar, then pour the hot vinegar in. Swirl the jar to ensure that everything is mixed thoroughly. Let rest for at least two weeks, swirling every few days, before using (this helps the flavors meld).
You can top your bottle of chiltepin sauce off with more white wine vinegar as it starts to get low if you like. I've found that I can do this a couple of times before it starts losing its potency and I need to order new peppers.