If you are offered dessert in an Iranian household it is customary to initially refuse the cake, cookie, fruit or whatever it is the first time you are offered it, no matter how much you want it. You insist that you are full, that you couldn’t possibly. The host gently pushes back, saying that the dessert will go to waste, that it’s really not that good anyway. There is an abundance of sweets and you have a large selection to choose from. After a couple more rounds you’ll end up with a chai and a sweet, and you don’t have to worry about losing out.
If you are offered dessert in a French household and you want to eat it, take it. Be clear that you’d like it. Take it. Take it the first time because you will not see that dessert again if you refuse. There is just enough dessert for the guests present and if you try to politely refuse your piece of cake, it will simply be divided up among the remaining guests. No second chances.
I’m sure I’m generalizing here a bit, but coming from a place where tarofing is expected, I was genuinely surprised when I had dinner with my French in-laws for the first time. It’s pretty stressful eating with your boyfriend’s parents when you don’t know the rules…they probably thought I was a little off for not wanting dessert or flaky for first saying no, and then yes. And I felt like I was in an eating frenzy, panicked by the thought that I might actually not be forced to eat dessert.
Even if by some freak occurrence you do not end up eating a sweet in the Iranian house, you can count on something being wrapped in aluminum and tucked under your arm on your way out the door. (At least, this is what I know of my Assyrian relatives.) The French traditionally don’t do leftovers. You will not get an extra lunch out of this dining experience.
But hey, once you know the rules, it’s easy to play. I just throw on a different cultural lens depending on my dining companions, and I always politely end up with dessert.