 Some discrepancy exists on the exact date when Morris created the popular cocktail . <unk> Dale <unk> asserts the drink was invented in 1915 , but other sources argue this happened in the 1920s . The Chilean web newspaper El Mercurio Online specifically contends historians attribute the year of the drink 's invention as 1922 , adding that " one night Morris surprised his friends with a new drink he called pisco sour , a formula which mixes the Peruvian pisco with the American sour " ( in Spanish : " Una noche Morris <unk> a sus <unk> con una nueva <unk> a la que <unk> pisco sour , una <unk> que <unk> lo <unk> del pisco con el ' sour ' <unk> . " ) . 
