1. Place the egg yolks, 5 ml (1 tsp) vinegar, mustard, garlic, salt and pepper in a blender or a food processor fitted with a steel blade (or, if you don't have one, into a mixing bowl and use an electric hand-held beater set at medium speed) and mix until well blended.
2. Add the oil, drop by drop at first until 60 ml (4 tbsp) has been used.
3. Add the remaining oil in a thin, steady stream, beating constantly (or with the motor of the blender or processor running).
4. Every now and then, don't add oil but continue beating to combine (emulsify) the ingredients thoroughly.
5. Add the lemon juice and the remaining vinegar just before use.
Makes 375 ml (1 1/2 cups).
Any of these flavourings may be incorporated at the end, after adding the lemon juice and vinegar: 5 ml (1 tsp) tomato concentrate (for a pink mayonnaise)
5 ml (1 tsp) grated orange or lemon peel
5 ml (1 tsp) capers
5 ml (1 tsp) stoned and finely chopped black olives
4-5 fresh basil leaves, finely chopped
5 ml (1 tsp) crumbled dried tarragon or a few sprigs fresh French (not Russian) tarragon
1-2 mashed anchovies
5 ml (1 tsp) mild curry powder.
To make fresh watercress mayonnaise: Trim 12-14 sprigs of fresh watercress, then blanch (plunge into boiling water for 2 to 3 minutes) and refresh (plunge into cold water). Very gently squeeze out excess moisture, using paper towels, then add to mayonnaise and blend until smooth.