The ornamental design for a sandal, as shown and described.
FIG. 1 is a front, left perspective view of a sandal showing my new design;
FIG. 2 is a front, right perspective view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top plan view of the sole portion of the sandal, for ease of illustration;
FIG. 8 is a bottom plan view of the sole portion of the sandal for ease of illustration; and,
FIG. 9 is a top plan view of the top portion of the sandal, shown in a flattened state, said portion covering the foot and having two side pieces which are applied under the sole of the she to form the anti-skid portion.