Bring vinegar, salt and sugar to simmer in a small pot. Cook just until salt and sugar dissolves.
Pour liquid over jalapeños.
Cover and let pickle in the fridge overnight. These will last a very long time in the fridge!**
Notes
* I highly recommend kosher salt for this, as the ratio of salt will be off if using a different salt. My favorite is diamond crystal kosher salt.** You can even eat these after just about 1-2 hours of pickling. The won’t be as pickled, but will still be quite tasty!