The star ingredient in Italy's most famous Parmesan dish, the worldly eggplant also appears in French ratatouille, Serbian ajvar and Middle Eastern baba ganoush. Varieties of this nightshade range from the deep purple or nearly black American globe eggplant to a softball-sized white Thai eggplant. The seeds make eggplant technically a fruit, though most culinary preparations treat it like a vegetable. For a larger or an older eggplant with a lot of seeds (the source of bitterness), a saltwater bath before cooking may improve the flavor of the flesh.
Fill a large bowl or pot with 4 to 6 quarts of cold tap water.
Add a 1/4 cup of kosher salt. Stir well.
Cut both ends off the eggplant about 1/2 inch deep. Stand the eggplant on one end, then shave the skin off by running the knife down the length of the eggplant. Repeat until you make it all the way around the eggplant.
Cut the eggplant into 1/2-inch-thick slices, a 1-inch square dice or 1/4-inch strips, depending on how you're going to use it.
Put the eggplant into the bowl or pot of salt water. Submerse it completely.
Soak the eggplant in the refrigerator for at least three hours or overnight. Drain it, rinse it in cold running water and pat it dry before using it in your recipe.