  In high energy nuclear collisions the leading parton of a jet can change
flavor through interactions with the surrounding medium. This can considerably
boost the relative yield of rare high momentum particles, like strange quarks
and photons. We revisit these jet conversions and discuss implications for the
azimuthal asymmetry $v_2$ of rare probes. We predict that the $v_2$ of kaons at
RHIC falls significantly below that of pions and protons at high transverse
momentum. Experimental information on the relative $v_2$ of strange hadrons
could provide constraints on the mean free path of fast quarks and gluons in a
quark gluon plasma.
