We present an Immersed Interface Vortex Particle-Mesh (IIVPM) method in 2D and validate our approach. Unlike other VPM-based approaches, it converges in time and space up to the boundary, and hence it offers a sharp and accurate way to take the presence of obstacles into account. We first present the methodology and investigate its convergence. We then apply it to the benchmark of the impulsively started flow around a cylinder at various Reynolds numbers (from Re=550 to Re=40 000) and, in particular, we highlight the gain in accuracy brought by the sharp interface treatment.