The last time I had a Pisco Sour was around 16 years ago when E. and I made our epic trip to Peru as part of our world tour of 1999. The town of Pisco in Peru is famous for the eponymous drink (made from recollection from egg white, lemon juice and a spirit called Pisco unsurprisingly made in the town) and of course we partook with enthusiasm during our visit. We even purchased a bottle (which we then proceeded to transport in our rucksack for the rest of the trip - E. eventually got sick of carrying it and decided to finish the bottle in our campervan in Adelaide during the Australian leg of our tour with hilarious (for me) consequences - it is quite strong!).
Anyway last night I went to the Peruvian restaurant in the Four Seasons. The food was excellent (certainly far superior to what we were eating on our 1999 visit to Peru.....) but the evening was made particularly memorable by my re-acquaintance with the Pisco Sour - it did seem significantly stronger than I remembered it - but that might be because I getting old - it certainly tasted very good and I will be definitely returning to that restaurant.