The ornamental design for a samplingdish, as shown and described.
FIG. 1 is a perspective view of a sampling dish showing my new design;
FIG. 2 is a top view thereof;
FIG. 3 is a first side view thereof;
FIG. 4 is a second side view thereof;
FIG. 5 is a front view thereof;
FIG. 6 is a rear view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines in the drawing views are included for the purpose of illustrating the unclaimed portions of the sampling dish and form no part of the claimed design.