If you are using a larger eggplant, place a few slices of eggplant in a colander (you can skip this step for Japanese eggplant). Add a sprinkle of kosher salt. Continue to add layers of eggplant alternating with generous sprinkles of kosher salt until all of the eggplant is salted. Let sit in a sink or over a plate for 30 minutes; you will start to see moisture beading up on the eggplant, and some liquid may collect under the colander.
Pat the eggplant dry with paper towels or a clean dishtowel. Brush the eggplant on both sides with olive oil.
Place the eggplant slices on the grill. Grill the eggplant, covered, for about 5 minutes until they get nice grill marks on the bottom and begin to soften, then flip them and grill for another 3 minutes or so.
Remove from the grill and serve warm or at room temperature.
Notes
The key to non-bitter eggplant, no matter how you are cooking it, is to salt it first. This isn’t necessary for very small or young eggplant without many seeds, like Japanese eggplant, but for larger eggplant, it makes a big difference. It’s easy to do; it just takes a few extra minutes.
You should feel free to move the eggplant about the grill to cooler spots if they look like they are browning too quickly. You can grill them for longer. If you want softer eggplant, just make sure to flip them as needed and not let the slices start to get too brown in any spots.