''Wow," Michelle says, nodding at a girl walking past. "Nice bun."
We've been noticing the buns for a few days now. Girls in Iran mightn't have quite the same freedom to express themselves in public as their counterparts in the Western world but they sure know how to do a bun.
They serve a dual purpose, these voluminous piles of hair. They're a way to keep stray strands under control, but for the young and trendy women of Tehran they're also an accessory, part of an artfully draped hijab that leaves hair and face on display.
The bigger the bun, it seems, the better. The bazaars here even sell fake bun extenders.
This is not something Michelle and I had expected. In fact we had no idea what to expect. For any Westerner it can be discombobulating enough travelling through the Islamic world, but for Michelle there was an extra level of intrigue: How would she be treated in Iran? How would she be expected to behave?
Before arriving it had been difficult to find answers to even the simplest questions. What should Michelle wear to respect local customs? Where could she go?
Could the two of us eat together in restaurants? Would we be riding together on the train? We weren't sure. Our plan was to figure these things out as we went along, to bumble our way through while hopefully remaining courteous and not breaking too many rules.
Hence the hijab Michelle has been wearing, although in her case without the fashionable bun.
Fashion is probably the last thing on her mind - just getting the headscarf to stay on is a challenge for the inexperienced.
Michelle's been trying a few approaches. There's the "foreign correspondent" look, where you drape the scarf over your head and then flick one half of it across your neck. But this is prone to falling off.
Then there's the more effective and complicated method that an African friend of Michelle's taught her - the scarf sits in place perfectly for the entire day but you almost need the Jaws of Life to prize it off at night.
In Iran women always have their hair covered in public places, although it's not long after we arrive in Tehran that we realise with the help of a bun, these rules can be stretched.
You see local women glide by on the street, long trenchcoats riding above high heels, their faces immaculately made up, and a headscarf draped gracefully to leave most of their hair uncovered.
They make it look easy. For Michelle and I, however, just leaving the hotel is a struggle. You know when you visit a freezing cold country like, say, Norway, and it takes forever just to put on enough clothes to leave the house? Iran is a little like that.
For Michelle the dressing process starts with jeans and then a skirt to cover the jeans. Then there's a top and then another, baggier top and then a scarf draped around the shoulders.
Then there's the headscarf. And then a pair of purple Ray-Bans. (Although that's a Michelle thing.)
Even with all of those measures she still gets looks, occasionally, as the two of us stroll around Tehran. "Everyone's staring at my feet," Michelle whispers one day. "Do you think it's because I'm wearing thongs?" She pauses. "Or because I painted polka-dots on my toenails?"
Hmm. Must be the thongs.
There are certain hindrances imposed upon a woman visiting Iran and one of the more tiresome for Michelle is having to pretend to be married to me. Travelling together as friends, we elected to pose as spouses to calm curious locals and hoteliers. So far, so good. And anyway, posing as my wife does have its attractions. Not only does Michelle get to be fake-wed to a world-famous travel writer but she didn't even have to apply for a visa to enter the country.
Upon arrival at Tehran airport, I simply listed her as my "accompaniment" and in she was stamped.
It's one of many surprises we've had in Iran, a place where my fake wife and I have been moving with freedom and ease. There's a women-only carriage in the Tehran metro but we choose to ride together in the mixed area. We also eat together in restaurants, where young couples hold hands and smoke cigarettes.
Turns out if you show Iran respect it will repay it many times over. Women approach Michelle constantly during our stay. School kids and uni students introduce themselves, giggling shyly. Michelle poses for photos. She's a rock star in purple Ray-Bans.
In fact the most difficult part of Michelle's experience has probably been getting dressed in the morning and then shedding all of the layers at night.
And fashioning a big enough bun.