Hold the eggplant by the stem and peel the skin. Then cut off the stem.
Slice the eggplants into 10–12mm thick slices (around 0.3–0.5 inches).
Depending on how many slices you have, place them in a large bucket or container.
Sprinkle a generous handful of rock salt over the slices, cover them with a tea towel, and place something heavy on top (like a timber board or any heavy object) to press the eggplant and help release moisture.
Leave it at room temperature overnight (about 24 hours).
After 24 hours, bring a large pot of water and white vinegar to a boil (use 2 liters of vinegar to 6 liters of water).
Drain the salted eggplant using a colander. Once the water is boiling, blanch the eggplant slices for 30 seconds.
Drain the eggplant again in a colander and place something heavy on top to squeeze out any remaining moisture. Let it sit for 5 minutes.
Spread the eggplant slices out on a clean, flat surface, cover with a clean towel or blanket, and let them dry for about 6 hours.