Cut the beet greens from the beets, leaving about 1 inch of the stems
attached to the beets, and reserve 16 of the beet leaves. Scrub the
beets, wrap them in small groupings tightly in foil and in a baking
pan roast them in a preheated 350F. oven for 1 to 1 1/2 hours, or
until they are tender. Unwrap the beets carefully, discarding any
liquid that may have accumulated in the foil, and let them cool until
they can be handled. The beets may be roasted 1 day in advance and
kept covered and chilled.

Rinse the reserved beet leaves, in a steamer set over simmering water
steam them, covered, for 1 minute, and transfer them with tongs to
paper towels to drain. In a small bowl whisk together the mustard,
the vinegar, and salt to taste, add the oil in a stream, whisking,
and whisk the dressing until it is emulsified.

Peel the beets and trim the stem ends flat. Standing each beet on its
stem end, cut parallel slices into but not through the beet at
1/4-inch intervals, stopping about 1/2 inch above the root end.
Rotate each beet 90 degrees and cut parallel slices in the same
manner to form a crosshatch pattern, keeping the stem end intact.
Arrange 4 of the beet leaves on each of 4 plates and arrange the
beets on the leaves. Drizzle the beets with the dressing and sprinkle
them with the scallions.

Serves 4.