In the past, eggplants were left to sit in a colander with salt on top to remove bitterness and drain excess moisture. However, nowadays, you don't have to do this because eggplants are selectively bred not to be bitter. Just sprinkle a pinch of salt on the eggplants before roasting them as a seasoning, not remove water. However, if you are deep frying the eggplant and want drier, less juicy eggplant slices, you can salt them with coarse salt and let them sit for 1 hour to purge some excess water. Then rinse them and pat them dry with a paper towel. Don't use fine salt because it penetrates the eggplant making it too salty. If you make roasted eggplants, there's no need to let them sit in salt because their water will evaporate while the slices cook in the oven.