Making tacit knowledge usable for companies has been a challenge. With the latest advancements in generative artificial intelligence (GenAI), developing and using assistance systems has become easier than ever. However, to create assistance systems, an initial base of expert knowledge is required. To establish a method for gathering domain-specific knowledge and especially tacit knowledge, location information, and information systems data, we conducted a design science research study. The designed “IRIS” method captures this information to create an initial spark that serves as the base for assistance systems in the maintenance domain. We demonstrate our method using the case of maintenance in the energy distribution grid and are able to derive an impressive knowledge collection with only a single workshop. The method allows practitioners to gather a wide range of domain-specific knowledge. Researchers in assistance systems and knowledge management can utilize the method for establishing baselines in knowledge collection from different source systems and extensions into GenAI.