1     Egg
     1   ts  Dry mustard
     1   ts  Salt
   dash  Cayenne pepper
     1   ts  sugar
    1/4   C  Olive oil
     1    C  Vegetable oil
     3    T  lemon juice

Put in the blender container: egg, mustard, salt, cayenne, sugar and olive oil.
Cover and blend on high until thouroughly combined.
With blender still running, take off the cover and slowly add 1/2 cup vegetable oil, and then the lemon juice until thouroughly blended.
Add slowly the remaning vegetable oil and blend until thick.

You may have to stop and start the blender to stir down the mayonnaise.

Yields 1 3/4 cup.