Hi Joe, thanks for reading, and thanks for the question!
I don’t have a set process for this that works for all organizations, but I think any discovery process that’s recursive will work. For example: start with an org chart and pick a few people on it, ask for 30 min meetings with them, and during these meetings ask them “What should I know about you, your project, or this org?” and write down projects, processes, referenced people. Then “recurse” on the newly discovered people: ask them for 30 min meetings, and ask them “What should I know about you, your project, or this org?” Repeat until you run out of new people to talk to. The more people referenced by project and process stories, the more explicit and implicit positional power these folks likely have.