Cooking the Aubergine: Peel, slice, and arrange the aubergine in a well-greased baking sheet. Brush or spray the aubergine with oil on both sides.
Bake for 10-20 minutes on 200C, then flip the aubergine on the other side and bake for more 15 minutes. Take the aubergine out of the oven and mash it coarsely using a fork.
Preparing the Dressing: In a mixing bowl, mix tahini and water well using a fork until the tahini become a bit liquidy. You may need to add more water. Make sure there are no clumps.
Add vinegar, salt, pepper, cumin, minced garlic, and olive oil to the tahini mixture, mix until all combined. Add the mashed aubergine to the tahini mixture and stir well.
Notes
I like to coarsely mash the egg whites; however, if you prefer a silky texture, you can simply blend all the ingredients in the food processor. (Don't run the food processor too much, just a few pulses).