"Underripe avocados are lightly pickled in brine that is tangy and slightly sweet. These are great to serve with your favorite burger, hot dog, or Tex-Mex dish. They make a snazzy addition to salads too! These are so addictive; I buy more underripe avocados than I do ripe ones now. I reuse the brine over and over. The brine can be reused by simply adding more avocados and allowing them to rest for 24 hours before consuming. These will last about 5 days in the refrigerator."
Combine vinegar and water in a saucepan. Stir in sugar and salt; add mustard seeds, dill, peppercorns, and habanero pepper flakes. Bring to a boil; stir until sugar and salt are dissolved. Remove from heat; cool to room temperature, about 15 minutes.
Divide habanero peppers and garlic clove between 2 canning jars. Divide avocado slices evenly between jars.
Stir vinegar mixture to evenly disburse seasoning; pour into jars. Close lids and place in the refrigerator. Chill until flavors combine, about 24 hours.