Pour 2 cups cold stock into a small bowl, sprinkle the gelatin over, and let stand a few minutes.

Heat the rest of the stock to simmering, add the gelatin mixture, and stir until completely dissolved.

Remove from the heat and refrigerate until it has become syrupy.

Line the bottom of a large bowl with about 1/4 inch of thickened aspic, chill until firm, then add another shallow layer of aspic. Place carrots, as many as you need to fit, in rows 1-1/2 inches apart on the bottom of the bowl. Put tiny onions in between. Cut the beet in decorative slices and place along the sides. Cover the vegetables with a thin layer of aspic and chill until firm.

Place the slices of beef upright through the center of the bowl, using remaining carrot cut in small pieces to hold them evenly apart. Pour in the remaining syrupy aspic to fill the bowl.

Refrigerate until firm, at least 6 hours-better overnight.

Unmold and serve with a mustardy mayonnaise.