You're going to Istanbul but make it sound as if it's a third world country.
Sure there are poor there - the population is huge and many have moved in from
all over Anatolia. But many have money - and Istanbul is as least a second
world city if not higher.

The reason you'll find plenty of vegetables and fruit is that the Turks love
them. I lived in Istanbul for two years and some of my best memories concern
all the wonderful fruits that came in season in such vast quantities.

It's not like going to the U.K. or Germany - in Turkey you'll have no trouble
finding veggies. I doubt if any other country has as many ways of cooking
eggplants.