Try adding plain yogurt to the grilled eggplant dip. It makes it creamy and gives additional tangy flavor. I’m from Middle Eastern origin and that’s how we did it back home.
I'm actually of Scottish/Irish descent, but many of my friends and coworkers are of Middle Eastern or Greek origin as well, and I have to agree with BBQ-Z here. This dip is a variant of baba ghanoush
and it's quite good, but adding yogurt makes it even better. (And it's one of the only ways I like to eat eggplant, too, because I don't like the skins at all.)
Another really great substitute for plain yogurt is Balkan-style or Greek yogurt. I grab the Balkan-style stuff wherever I can - it's about 3% butterfat rather than 1% or fat free, but it has a very rich texture like full-fat sour cream. And the taste is much tangier than regular plain yogurt so it really enhances the flavor of dips.
I also use it in place of sour cream, and for Greek tzatziki
there's really no substitute, either.