Reconfigurable optical logic gates are developed through the design and optimization of a metallic grating with a colloidal nonlinear dielectric. The device has a structurally enhanced nonlinearity, improving power consumption and speed. Detailed design strategy and simulations for several common logic gates are provided. Using materials readily available in common CMOS processing technologies, the gates switch in sub-picosecond scales with a driving irradiance of around $200; {{\rm MW/cm}^2}$.