The Physical Sciences Data Infrastructure (PSDI) aims to accelerate research in the physical sciences by providing a data infrastructure that brings together and builds upon the various data systems researchers currently use. Our webinar series provide updates on our exploratory pathfinder work, and on relevant tools and technologies that have been developed by members of our community. This record contains a more detailed version of the presentation that was presented at the "Once upon a Data Steward" webinar presented by Dr Samantha Pearman-Kanza on 10th July 2025. The recording of this webinar is available on YouTube: https://youtu.be/e0T4XEsMFFA Abstract: This webinar explored the growing importance of data availability and management in modern research. The session introduced the emerging role of the Data Steward, a new type of digital Research Technical Professional (dRTP) who ensures data quality and usability throughout its lifecycle. The webinar also unveiled CaSDaR (Careers and Skills for data-driven Research), a new four-year initiative designed to support and empower Data Stewards as central figures in the research lifecycle.