Like most things it's easier than you might think.
If you are using eggplant for a recipe the important thing is for it to be very, very
Poke a bunch of holes in the eggplant and put it in a baking dish that is big enough to lay it down.
Bake at 400F, keeping your eye on it until it deflates. You might have to poke it an turn it to get all the juice out but it will deflate after an hour, hour and a half. Remove and compost the skin.
Now you have a large bowl of roasted eggplant that is ready to bend to your will. Make sauce, relish/pickle, soup, dip, casserole, freeze it and save it for later, puree it and make crackers, let your imagination take you where it will with roasted eggplant.