Spread a bit of oil on the eggplant and put it on the grill, rotating periodically.
Meanwhile, chop tomato and onion and combine in a bowl.
Once eggplant is charred from the outside and soft on the inside (about 35 minutes depending on the heat of your grill), remove from grill and take out the innards (discard the charred skin).
Add the eggplant to the chopped tomato and onion and "cut" if some pieces are to long.
Add olive oil, salt and pepper to the spread and mix well. Serve.