Coherent interaction between a quantum dot and a resonant laser is observed through an incoherent read-out channel created by coupling to an off-resonant cavity. Under bichromatic driving of the quantum dot optical output collected from the off-resonant cavity exhibits two peaks, a signature of Rabi-side bands that matches closely with our theoretical model. The off-resonant cavity provides a convenient method for resonant quantum dot spectroscopy and quantum dot state readout.