3 Egg yolks (use large free range eggs)
10 oz. Oil ( Sunflower or Olive)
Pinch Salt
Grinding of Black Pepper
1 Tbs. Wine or Cider Vinegar

Have ready:
A small electric beater
A narrow bowl not much bigger than the diameter of the beaters.
Eggs at room temperature
The oil in a jug with a good pouring spout.
Put the egg yolks into the bowl and beat briefly just to break up.
Season with the salt and pepper.
Turn on the beater and dribble the oil on to the blades so that it is blended into the yolks as you pour. This way you can pour at a steady stream rather than drop by drop. When the mayonnaise gets very thick add the vinegar and then continue adding the oil. The entire job (with practice) takes no longer than 3 mts. ( about as long as it would take you to open the jar in the fridge)
Variations;
Aioli :- Add a crushed clove of garlic to the yolks and proceed as above.
( Excellent with fish)

Rouille :- Add garlic as in Aioli and stir in a tsp. Tomato puree and a finely
chopped red pepper at the end. Essential ingredient in French fish
soups.

Dill or Tarragon Mayonnaise (with a generous addition of the herb in
question-finely chopped- are delicious with cold chicken and salmon respectively.