  Organic salts represent an ideal experimental playground for studying the
interplay between magnetic and charge degrees of freedom, which has culminated
in the discovery of several spin-liquid candidates, such as
$\kappa$-(ET)$_2$Cu$_2$(CN)$_3$ ($\kappa$-Cu). Recent theoretical studies
indicate the possibility of chiral spin liquids stabilized by ring-exchange,
but the parent states with chiral magnetic order have not been observed in this
material family. In this work, we discuss the properties of the recently
synthesized $\kappa$-(BETS)$_2$Mn[N(CN)$_2$]$_3$ ($\kappa$-Mn). Based on
analysis of specific heat, magnetic torque, and NMR measurements combined with
ab initio calculations, we identify a spin-vortex crystal order. These
observations definitively confirm the importance of ring-exchange in these
materials, and support the proposed chiral spin-liquid scenario for triangular
lattice organics.
