I usually trail brake pretty heavy and deep into that left hander...I catch a lot of people there. I gave it a little too much brake and the rear came around a little too much. Then I needed to go right so I gave it throttle...probably a little too much...which caused the rear to oscillate back.
Basically I gave it more throttle when the car was already osciallting.
2015 F34 328iX GT Glacier Silver
2011 E90 M3 Monte Carlo Blue
2004 E46 M3 Imola Red