Version I tried today:
One large eggplant (made soft in oven)
4 tablespoons tahini*
Juice from 1,5 lemons
1 tablespoon olive oil
A pinch of ground cumin
Mash together with fork.
Oops, now I realize I forgot the garlic!
*) I used a rather dark tahini. Maybe white tahini is better for baba ghanoush?