The other day in the San Telmo markets in Buenos Aires I committed a great faux-pas. I touched the fruit at one of the grocery stalls. Avocados, specifically. I did know that you´re not meant to touch but it must have slipped my mind when I saw some ripe, voluptuous avocados just begging to be squeezed. ¨Are you going to buy those?¨ asked the woman at the store. ¨How much are they?¨ I asked back. Turns out they were twice the cost of the ones I´d just passed at another stall. So no, I said. ¨Well, you´ve been putting your hands all over them and having a feel,¨ she barked. And that´s when I remembered. You never touch the fruit and vegetables here. Instead, you ask for what you want and they pick and pack it for you. The lesson learnt was as firm (yet tender) as the avocados I ended up buying at half the price and spreading on my toast the next morning for breakfast.