I'd recommend an Iranian film called Children of Heaven, which came out in the late nineteen-nineties. I'm a civil engineer from Tabriz, now working in Germany, and it's the film I always suggest when colleagues ask about Iranian cinema.
I first saw it when I was about ten, at a school screening, and then again a few years ago with some German friends. The story is very simple. A young boy called Ali takes his little sister Zahra's pink shoes to be repaired and accidentally loses them. Their family is poor, and they don't want to worry their parents, so the brother and sister secretly share Ali's single pair of trainers. Zahra wears them to school in the morning and then runs back so Ali can wear them in the afternoon. Later, Ali enters a long-distance running race because third prize is a new pair of shoes, and he desperately tries to come third, not first.
I think foreigners should watch it for several reasons. Firstly, it shows a side of Iran that people abroad rarely see. The news usually talks about politics, but this film shows ordinary families, narrow streets in south Tehran, kind neighbours and children playing. My German friends said it completely changed their image of the country. Secondly, it's universal. You don't need to know anything about Iran to understand love between a brother and sister. And finally, it's beautifully made without any special effects. The race scene at the end is incredibly tense, even though it's just a boy running. It's suitable for all ages, so it's a perfect introduction to our cinema.