Eggplants are porous and easily soak up liquid. To reduce the amount of oil an eggplant soaks up in cooking, it is important to salt the slices or halves first. Doing this draws out the moisture present in the eggplant and helps reduce the oil uptake. However, even with salting, eggplant will absorb quite a lot of oil, so it's helpful to expect this to happen and account for it when cooking eggplant.