I claim the ornamental design for a portable food turntable, as shown and described.
FIG. 1 is a perspective view of a portable food turntable showing the new design.
FIG. 2 is a front side elevational view thereof.
FIG. 3 is a top elevational view thereof.
FIG. 4 is a right side elevational view thereof.
The left side elevational view is a mirror image of the right side elevational view.
FIG. 5 is a back side elevational view thereof; and,
FIG. 6 is a bottom side elevational view thereof.
The broken lines depict environmental subject matter and form no part of the claimed design. Additionally, the broken line details of the surface in FIGS. 1 and 3 form no part of the claimed design.