Omitting salt, begin by cooking the asparagus according to the package directions. Drain well, and then transfer to a serving dish to keep warm.
Blend together the egg, sugar substitute, and cornstarch. In a small skillet, melt the margarine and then add the egg mixture to it. Continue to cook over medium heat until the mixture thickens. Stir in the lemon juice.
Continue to cook until the sauce becomes thickened and bubbly.
To serve, pour the lemon egg sauce over the asparagus and sprinkle with lemon rind.