  Supermassive Binary Black Holes (SMBBHs) with sub-pc separations form in the
course of galaxy mergers, if both galaxies harbour massive black holes. Clear
observational evidence for them however still eludes us. We propose a novel
method of identifying these systems by means of reverberation mapping their
circumbinary disk after a tidal disruption event has ionized it. The tidal
disruption of a star at the secondary leads to strong asymmetries in the disk
response. We model the shape of the velocity--delay maps for various toy disk
models and more realistic gas distributions obtained by SPH simulations. The
emissivity of the ionized disk is calculated with {\em Cloudy}. We find
peculiar asymmetries in the maps for off center ionizing sources that may help
us constrain geometrical parameters of a circumbinary disk such as semi-major
axis and orbital phase of the secondary, as well as help strengthen the
observational evidence for sub-parsec SMBBHs as such.
