The ornamental design for a single foodservice unit, as shown and described.
FIG. 1 is a front perspective view of a single foodservice unit illustrating the invention design of flanking free-standing pylons on each side of the typical foodservice unit,
FIG. 2 is a rear perspective view of the foodservice unit of FIG. 1; and,
FIG. 3 is a front elevational view thereof.
The broken lime showing of a typical foodservice counter and hanging signs is for illustrative purposes only and forms no part of the claimed design.