In a 1 cup microwaveable liquid measuring cup, combine the egg substitute and the spread. Microwave on low (20%) for 1 minute, stirring once halfway through cooking, until the spread is softened.
Stir the lemon juice and mustard into the egg substitute mixture. Microwave on low for 3 minutes, stirring every 30 seconds, until thickened. Stir in the pepper.
If the mixture curdles, transfer to a blender and process on low speed for 30 seconds, until smooth.