In this paper we present a trust-oriented method that can be used when building P2P recommender systems. We discuss its benefits in comparison to centralized solutions, its requirements, its pitfalls and how these can be overcome. We base the formation of trust on evidential reasoning and designed with ease of adoption by existing infrastructures in mind. The paper includes a first analysis of performance based on a simulation used to investigate the impact on scalability and thus show the applicability of the protocol