OK, I have some interesting intelligence about the ingredients in Zankou's Garlic Sauce.
I introduced my team at work to Zankou last Friday. Even the timid among them loved it. They also demolished the falafels and mutabal. If you've never had the mutabal (pureed roasted eggplant) do yourself a favor and try it next time you go!
Anyway, one of the women gets very ill when she eats potatoes so we always know to warn her off them. I assured her that there was nary a potato in Zankou's kitchen. WRONG. After eating she felt mildly queasy.
On the way home from work she stopped at her local convenience store. She's friendly with the Middle Eastern family that runs it. She was chatting with them about having had Zankou for the first time, and her stomach upset and the potato problem. They assured her there are mashed potatoes in the garlic sauce!
Luckily, since she'd only had a tablespoon or two of garlic sauce, her distress was pretty mild, but I have to admit, I'd never suspected potatoes as one of the ingredients of this addictive schmear!