1 egg yolk, at room temperature
1 tbsp. white vinegar
1 tsp. Dijon mustard
11/4 tsp. salt
1/2 tsp. freshly ground black pepper
1 cup vegetable oil

Makes 1 1/4 cups

Recipe from Chatelaine Cook Book
 

By Hand:
In a medium size bowl, whisk the egg yolk, vinegar, Dijon, salt and pepper together.

Whisk in the oil, drop by drop at first, until the mixture begins to thicken.  Then, whisk in the oil 1 tsp. at a time, making sure the oil is completely absorbed before the next addition.  Taste and add more salt and pepper, if you wish.  Mayonnaise may be used right away.  Or, if you prefer, cover and refrigerate for 2 to 3 days.

In a Blender or Food Processor:
Place all the ingredient (except the oil) in a blender or food processor fitted with a metal blade.  Whirl until well blended.

With the motor running, add the oil, drop by drop at first, until the mixture begins to thicken.  Then, add the oil in a slow thin steady stream until the oil is absorbed.  Taste and add salt and pepper, if needed.  Use right away or cover and refrigerated 2 to 3 days.

Note:
Making homemade mayonnaise is easy if you keep these points in mind:

Start with room temperature ingredients.  Whisk the oil in drop by drop at first, then in a slow steady stream until the emulsion occurs.

If the mayonnaise curdles, don't panic.  Just whisk another egg yolk in a clean bowl, then whisk the yolk into the curdled mayonnaise, drop by drop, then in a slow steady stream until combined.