If you have a really fresh eggplant, which will have taut, shiny skin and will feel heavy for its size, there’s no need to salt it before cooking. However, if your eggplant isn’t so fresh (it will be a bit soft in places with duller, sometimes wrinkled skin), I recommend salting the slices before cooking. Salting the eggplant draws out moisture and bitterness (which is more prevalent in older eggplants) and will make the slices firmer on the grill (I include instructions in the recipe).