Here, we designed and synthesised colloidal Fano-resonant plasmonic nanoparticles-consisting of a goldintragap head and silver-body-termed "nano-Fanowmen," which exhibit a pronounced Fano dip in their colloidal spectra and Fano resonance-based SERS (Fano-SERS) signals. By integrating all available resonant components into the nano-Fanowman particles to fully maximise the SERS signal, we demonstrated a singleparticle Fano-SERS signal even at a low laser power of ~1 nW, a significant advancement compared to typical ~100 μW powers used in single-nanoparticle SERS studies.