We introduced recently a new theoretical scheme which accounts for hydrodynamically expanding bulk matter, jets, and the interaction between the two. Important for the particle production at intermediate values of transverse momentum (p_t) are jet-hadrons produced inside the fluid. They pick up quarks and antiquarks (or diquarks) from the thermal matter rather than creating them via the Schwinger mechanism -- the usual mechanism of hadron production from string fragmentation. These hadrons carry plasma properties (flavor, flow), but also the large momentum of the transversely moving string segment connecting quark and antiquark (or diquark). They therefore show up at quite large values of p_t, not polluted by soft particle production. We will show that this mechanism leads to a pronounced peak in the lambda / kaon ratio at intermediate p_t. The effect increases substantially with centrality, which reflects the increasing transverse size with centrality.