Anyone who knows me well, will know that I make my own mayonnaise. I get this from my mother who was in her 70s before she even allowed purchased mayonnaise to sully her fridge. Which incidentally, is her fridge and not public property (subject of another post). My beloved prefers commercial mayo for certain things but I rarely do. We recently made 2 litres of the stuff for a friend's wonderful Xmas party and usually I make it by hand because it's not that hard to do and you can stir and pour whilst conversing, or drinking a glass of wine.
I learned, early on, that it's the acidity that allows the emulsion to occur and maintains it. My first father-in-law (who was a nuclear physicist) imparted this gem of culinary chemistry to me and suggested always mixing mustard with the egg yolk to begin with. Gentle reader, he was right. A Breton friend with whom I shared this nugget of info, merely shrugged and said "Mais bien sûr!" For a while, I made whole egg mayo using the Kenwood blender (O trusty Kenwood Chef) but what a pain it was to clean everything afterwards, so I reverted to the bowl and wooden spoon method, with an experimental attitude to quantities. Experience led me to believe that the temperature of the ingredients made little difference to the outcome but it is important not ot shock the emulsion by adding too much oil at once.
As per the father-in-law, I always start with mustard - Dijon, naturellement, because that's the one I grew up with and the only mustard I really like, and I'm making the mayo. Sea salt & black pepper. Cider vinegar because it doesn't change the colour like our homemade, red wine vinegar does, and I think that lemon juice is acidic without body. Sunflower or peanut oil (you can use canola but I think it is the spawn of the devil and use it in nothing - ditto soybean oil). And then often I add a proportion of olive oil, depending on how strong the flavour of the oil is and what you are going to do with the mayo. I like a little olive oil but too much can make the mayo bitter. Of course, you can add garlic (sometimes I use homemade garlic olive oil and that's delicious) and herbs, sorrel makes a lovely, fresh, green mayo, tomato purée for Sauce Aurore, wasabi for kicks and so on.
Yesterday, at breakfast, I was reading the Saveur 100 Cooks' Edition which has some interesting stuff in it (see http://www.saveur.com/) and came across this intriguing snippet about a 20 second mayonnaise. I thank chef Matthew Rudofker for this piece of genius, for which you must own or borrow an immersion or stick blender.
You shove all the ingredients in a tall beaker, put your immersion blender (not the whisk) flat on the base of the beaker, blend for 3 seconds and slowly pull the blender up through the oil, which emulsifies as you go. The recipe says it takes 17 seconds for it all to emulsify but I reckon it was about 7 secs. and I was counting. The result is excellent according to my taster and Duke's mayo devotee (Duke's in the Eastern US and Best Foods in the West).
This isn't a good photo but it is good mayonnaise
1½ Tbsp vinegar
1 Tbsp mustard
½ tsp salt
2 cups oil
So easy and the bonus is that you can keep it in the fridge for a month, if it lasts that long!
Post scriptum: We ate some for lunch with the leftover poached Alaska salmon and the taster now believes that we need never buy mayonnaise again...and also - isn't mayo amazing stuff? I used to think that the Duc de Mahon's cook invented it on a battlefield but Wikipedia tells me that it is not so http://en.wikipedia.org/wiki/Mayonnaise but I will still refer to it as mahonnaise for my own pleasure.