Sterilize the canning jars. Rinse the eggplants and remove the stems. Make a lengthwise slit on one side of each eggplant.
Place the eggplants in a laminated pot, cover with vinegar, bring to a boil, and simmer over medium heat for 5 to 10 minutes or until soft (do not overcook). Drain the eggplant, discarding the vinegar.