How to preserve eggplants/brinjals?
There's a Sicilian preservation of eggplant called Melanzane Sott’Olio.  It's similar to giardiniera, but after pickling, you pack it in oil.  

Because of the botulism risk of putting garlic in oil, it's considered risky for long-term storage (more than a week, and that's refrigerated), even though it was used in Sicily for generations.  You might be able to replace the garlic with something safer, or omit it entirely.