Mayonnaise

Food in England, Dorothy Hartley, p. 220

2 egg yolks
__ salt
__ pepper
__ dry mustard
1 Tbsp (or more) tarragon vinegar
1 pint salad (ie. bland) oil

1. Whisk the eggs, salt, pepper and mustard until the yolk turns a pale yellow ('start the cream').
2. Continually whisking, very slowly, in small quantities and alternately add the vinegar and the oil. Whisk constantly until the characteristic thick cream is formed.
3. In hot weather work in a cold room or in a chilled bowl