  We use numerically exact quantum dynamics calculations to demonstrate
universal stereoselectivity of cold collisions of $^2\Pi$ molecules with
$^1$S-state atoms in an external electric field. We show that cold collisions
of OH molecules in their low-field-seeking $f$ states, whose dipole moments are
oriented against the field direction, are much more likely to lead to inelastic
scattering than those of molecules oriented along the field direction, causing
nearly perfect steric asymmetry in the inelastic collision cross sections. The
universal nature of this effect is due to the threshold suppression of
inelastic scattering between the degenerate $\pm M$ Stark sublevels of the
high-field-seeking $e$-state, where $M$ is the projection of the total angular
momentum of the molecule on the field axis. Above the $\Lambda$-doublet
threshold, the stereodynamics of inelastic atom-molecule collisions can be
tuned via electric-field-induced resonances, which enable effective control of
Ne + OH scattering over the range of collision energies achievable in current
merged beam experiments.
