Peel the eggplants and cut them into long strips about ¼ inch thick. Try to keep the strips similar in size so they soften evenly.
Place the eggplant strips in a large bowl and sprinkle with the kosher salt. Toss well, then set a plate directly on top of the eggplant and weigh it down lightly. Let it rest for 6 hours at room temperature.
Transfer the salted eggplant to a colander. Press firmly with your hands to squeeze out as much liquid as possible.
In a large saucepan, bring the white wine vinegar and water to a boil over medium-high heat.
Add the eggplant strips and cook for 3 to 4 minutes, just until they are tender and flexible. They should still hold their shape.
Lift the eggplant out with a slotted spoon and spread it over a clean tray or large plate. Let it cool for 10 minutes, then press gently again to remove extra moisture.
In a bowl, combine the garlic, parsley, oregano, red pepper flakes, mustard seeds, black peppercorns, and ¾ cup olive oil.
Add the cooked eggplant to the seasoned oil and toss until the strips are evenly coated.
Pack the eggplant into a clean glass jar, spooning in some of the garlic, herbs, and spices between the layers.
Pour in enough extra olive oil to fully cover the eggplant. Press down gently with a spoon to release trapped air, then top up with more oil if needed.
Seal the jar and refrigerate for at least 24 hours before serving.