Dear Dr. XX,
It was very nice to talk to you last Wednesday and thank you very much for your time. Regarding the on-site interview you mentioned during the interview, I will be very happy to give a 15-30 minute presentation and the topic can be sent to you once the on-site schedule is confirmed. So far, I haven’t received the call from your HR staff. I would appreciate it very much if you could let me know the update.
Sincerely,
xxx