All along their careers, surgeons learn through mentoring, operating on patients side-by-side with expert surgeons. However, access to experts is more and more challenging as they are often located far from learners. Telementoring can increase the reach of mentors by supporting mentoring at a distance, but despite their potential, current systems remain rarely institutionalized. We investigate current surgical mentoring practices, to inform future design of telementoring systems in providing support for learning. In a field study, we observe 11 surgeries and conduct follow-up self-confrontation interviews with mentor-mentee pairs. Through Thematic Analysis, we find that the domain of surgery results in mentee's needs for reassurance regarding safety, being spared from workload and risk, both essential to support the acquisition of skills. Second, that mentors understand the situation primarily through the surgical site view but also through inspecting the mentee's posture and the patient's body. Thirdly, that mentors take physical distance as their presence limits mentees' autonomy development. We discuss the limits of current surgical telementoring systems and rethink their role as companions of onsite mentoring.