How to make mayonnaise

ayonnaise is easily Russia's national dressing. Although often derided as fatty and unhealthy, in Russia it outsells every other type of commercial condiment including ketchup: the Guinness Book of Records insists that the Russian city of Ekaterinburg is world's leader in mayonnaise consumption.
A Ekaterinburg-native friend of mine told me that when back in the 90s Russian factory workers tried to mess with the newly imported Italian mayonnaise-making machinery by using less expensive ingredients and more water, it would stop working. According to him, that's why Eketarinburgers have been enjoying properly manufactured mayo ever since.
It is somewhat ironic that the jarred variety with all the creepy chemical additives, very likely substandard eggs, inexplicably added sugar and excess of salt is so popular despite mayonnaise being one of the simplest and cheapest sauces to make at home. It takes just about 5 minutes to whip up a bowl of mayonnaise. Here how it goes:

1. Mix well one very fresh egg yolk (I buy biodynamic free-range organic eggs from Orchard eggs) with a tablespoonful Dijon mustard. Both need to be room temperature.
   
2. Add little by little one glass of your favourite vegetable oil while whisking vigorously making sure that all oil is incorporated in the mixture before adding any more. Only use up to 30% of olive oil as it tends to make your mayonnaise taste bitter.
   
3. Now for the flavouring. Mix one tablespoonful aceto balsamico bianco, some finely ground sea salt and freshly ground black pepper to taste, and whisk the mixture in. That said, I use Thai fish sauce instead of salt for the extra kick and add crushed garlic to make aioli. You can also add finely chopped estragon, anchovies, etc. - let your imagination run free!
   
4. In case your mayo comes out too thick, whisk in a tablespoonful of water.