This article reports on the findings from a technology-enhanced teacher learning project where the SETTVEO app (Self Evaluation of Teacher Talk through Video Enhanced Observation) was used to support teachers’ reflective practices and professional development. Participants in the project were a group of 40 student teachers (ST) from Hong Kong, who took part in a teaching practicum taught online owing to COVID-19 restrictions. They formed online professional learning communities (PLCs) with peers and tutors, shared their class recordings (tagged using the on SETTVEO app), and reflected on their teaching through weekly discussions. This study aims to characterize teacher learning mediated by video technology and dialogue, and to evaluate the impact of the app on STs’ reflective practices and emerging Classroom Interactional Competence (CIC, Walsh 2013). In this article, we focus on an individual ST's development over a period of eight weeks. Two sources of data are transcribed and analysed using an applied Conversation Analysis (CA) method: the first records the teacher's interactions while teaching, the second their dialogic reflections based on observations of these class recordings. Findings from the study enhance our understandings of the role of technology in influencing classroom practice and highlight its importance in promoting teacher noticing and professional development. © The Author(s) 2023.