I think the white sauce at the halal truck in NY is mayonnaise based, but have no clue about other ingredients. It really is delish. I do wonder what the lamb gyro is mad eof? hmm. But I know the chicken gyro just uses cooked chicken breast meat etc...but just not sure of spices used. I seen some recipes online where they just use oil/salt/pepper & dill, but that doesnt seem quite right.
I could be wrong, but I thought Lamb "Doner" is typically an afghani/Turkish staple, which is just like their version of our seekh kebab.
In England, Doner is Turkish, the english ppl love to have a doner kebab just after they get tanked up and spill out of the pub... a short while later it ends up on the street in vomit form. Sicko's!
Ahem, aside from that, people of other ethnic origins are found to appreciate it in a non-drunken state.