Athenian mayonnaise

Dissolve the corn flour in a glass of water. 

Continue by boiling it so it will turn into cream. 

Let the cream cool in a deep porcelain bowl. Add the egg yolk and whisk until integrated. 

Add the oil little by little while whisking. When the oil is integrated, add the mustard, salt, pepper and lemon. 

Taste to see if the mixture is adequately tasty and a bit tart. Then it is ok.