1. Place the egg and lemon juice in a blender or food processor. Let them come to room temperature together, about 30-60 minutes. Add the dry mustard, salt, and 1/4 cup of the oil. Whirl until well mixed – about 20 to 30 seconds.
THIS IS THE IMPORTANT PART!
2. The only remaining job is to incorporate the remaining 1 cup oil into the mixture. To do this, you must pour very slowly… the skinniest drizzle you can manage and still have movement in the oil. This takes about three minutes or so. Think about three minutes during a WOD; it’s a fairly long time. Breathe. Relax. Drizzle slowly.
If you’re using a blender, you’ll hear the pitch change as the liquid starts to form the emulsion. Eventually, the substance inside the blender will start to look like regular mayonnaise, only far more beautiful. Do not lose your nerve and consider dumping! Continue to drizzle.
If your ingredients were all at room temperature and you were patient, you will be rewarded!