Lean Startup lacks a method specifically designed to evaluate whether a HCI-design is fulfilling the promises delivered by the unique value proposition (UVP). At the time of writing, concurrent think aloud protocols during usability testing and interviews are used to that end. There are, however, a couple of issues bundled with the use of such methods. Using a case study conducted on two iterations of high-fidelity prototypes of a meal planning website currently in development, a method called Directed Product Reaction (DPR) is proposed. DPR is a result of the adaptation of Product Reaction Cards, and the addressing of issues uncovered during case study iterations. DPR aspires to be that specifically designed method needed for assessment of user experience in relation to UVP in Lean Startup, and while the resulting method proposed has far from achieved that goal, it serves as a foundation moving forward.