We introduce a concept of resonant tunneling photonic nanotriod which makes possible mutual control of cross-cut light flows. The idea of this concept is based upon strong resonant interaction between near phase-matched quasi-localized eigenmodes of nonlinear planar dielectric waveguide and incident beam. We demonstrate that by means of variation of input guided wave intensities even small nonlinear phase mismatches may switch the bistable system from one equilibrium state to another and back that results in deep modulation of beam reflection and transmission coefficients due to the exchange between trapped and free photons. Suggested nano-size device can also serve as light amplifier, light modulator, controlled coupler or light flows divider, etc.