Salzburg took in their first ever clash in the Champions League last 16 when hosting the German giants and Aaronson lined up in the no 10 role behind front pair Karim Adeyemi and Noah Okafor.
After just 21 minutes, Aaronson provided the assist as early substitute Chukwubuike Adamu gave Salzburg a 21st-minute lead, Aaronson poking Adeyemi's cross into the path of Adamu who supplied a clinical curling finish from just inside the box.
Aaronson raced off to celebrate and the 21-year-old went on to create four more chances after making five key passes in the contest as a whole, becoming the youngest player in Champions League knockout history to achieve such a feat since a 20-year-old Lionel Messi managed the same for Barcelona against Celtic in 2008.
Aaronson and Salzburg were heading for a famous first-leg victory against Bayern until Kingsley Conan equalised in the 90th minute.
Leeds wanted to sign Aaronson in the January transfer window but the Austrian outfit were unwilling to part with the US international, despite bids of £15m and £20m.