I have just emerged, boggle-eyed from the lab....
To start with:
2 yolks from pricey fresh Waitrose eggs (at room temperature)
Salt
Black pepper
Juice of half a lemon and a dash of white wine vinegar
A heaped teaspoon of Dijon mustard
Put all this stuff in deep bowl and blend it with a hand held blender (Argos do some electric stick blenders for about six quid)
The oil mixture:
100ml rapeseed oil
100ml grapeseed oil
50ml extra virgin olive oil
Put the oil in a small jug and add it to the eggs etc very, very slowly while you blend away. To begin with, add the oil drop by drop. Don't rush it. It helps if you move the blender up and down so that mixing is more uniform.. The mixture will start to thicken. When it does, you can add the oil more quickly. When you have added all the oil, you should have a lovely thick yellow mayonnaise.. I added half a dozen mashed capers and a crushed garlic clove at the very end.
IMHO, it's quite good. Alas, my food photography leaves a lot to be desired.
All that remains to be done is to invite
@threebikesmcginty round to sample it.
EDIT: The yellow colour comes from two ingredients
1) Waitrose's Clarence Court Burford Brown egg yolks
2) Farringdon's Mellow Yellow Cold Pressed Rapeseed Oil