The improved apparatus includes an improved extruder die assembly comprising a forming section, an injection section, and a converging nozzle section having axially aligned ridgelines which gradually project into the bore of the nozzle as the nozzle converges to gradually disrupt the axial flow of an extrudate at specific peripheral points thereby altering the extrudate's velocity profile. By gradually disrupting the axial flow in close proximity to the projecting ridgelines prior to its extrusion, the dimensional quality of the resulting direct expanded food piece is greatly improved. Moreover, by carefully positioning the capillary channels of the injection section into that portion of the flowing extrudate not affected by the axially aligned ridgelines, a distinct colored and/or flavored pattern is imparted into the extrudable food mass during the extrusion process while improving the quality of dimensional design aspects of the resulting extruded, complexly shaped, direct expanded food products.