A reliable measure of the adhesion between a very deformable material and a solid surface is rather difficult, since the interface boundary conditions and the bulk deformation of the layer are closely and very nonlinearly coupled. In this article, a new methodology to assess the adhesion of a soft viscoelastic layer on a solid surface is proposed, where we have used a specific experimental geometry minimizing the bulk deformation of the layer. A flat-ended probe is first put in contact with a thin layer of soft material and removed at a constant velocity. The probe is then stopped at a preset level of tensile force and the time for complete debonding of the layer from the probe is measured. For our model system, comprised of a soft acrylic removable adhesive and a silicone-coated surface, the higher the applied force the faster the interfacial fracture occurs, leading to an experimental curve of the adhesion energy as a function of average crack velocity. We find that the methodology is relatively simple to implement and should be widely applicable for weakly adhering soft layers of arbitrary viscoelastic properties. The assumptions involved in such an analysis and their inherent limitations are also illustrated experimentally and critically discussed.