I claim the ornamental design for a portable storage container, as shown and described.
FIG. 1 is a perspective view of a portable storage container, with one of the drawers illustrated in the extended position, showing the new design thereof.
FIG. 2 is a front side elevational view thereof.
FIG. 3 is a back side elevational view thereof.
FIG. 4 is a left side elevational view thereof.
FIG. 5 is a right side elevational view thereof.
FIG. 6 is a top elevational view thereof.
FIG. 7 is a bottom elevational view thereof; and,
FIG. 8 is a perspective view of the portable storage container, with one of the drawers as illustrated in the resting position.