Every company, in a knowledge-based economy and, in a sustainability-aware era, is “doomed” to deal with a critical mass of strategic assets, in order to achieve a sustainable competitive advantage. Maintaining this system up-to-date requires financial/organizational efforts. Therefore, in order to optimize performance, it is necessary to detect which are the assets that can be outsourced/externalized without jeopardizing the business model architecture. Nevertheless, several studies confirm the inherent risks upcoming with any decision of outsourcing; pursuing a bearable long-term advantage over competitors mostly involves combinations of resources and capabilities, i.e., intangible assets. By the means of a multi-criteria indicator, the proposed framework builds a quantitative relational ranking of such resources, disclosing their critical weight (revealing which assets are actually strategic), hence the convenience for each of them to be outsourced or kept “in-house” to create sustainable value. This solution permits a strategy-level prioritization to take informed decisions on outsourcing candidates, also returning further analytics on the status of each investigated entity. Designed as a discriminating tool in make/buy resolutions to be used alongside traditional cost-based criteria, it represents a comprehensive approach capable of appreciating the complexity of the problem and the involved risks in order to keep a sustainable momentum.