Put the 100 ml of sunflower oil and garlic cloves in a small pan and place in the oven for 30-45 minutes, or until the garlic is soft. Take the garlic out with a slotted spoon and allow it to cool at room temperature.
To make the aioli, put the garlic, egg yolk and mustard in a food processor and blitz to a paste. Gradually add the rapeseed oil and continue mixing until you get a thick sauce. Season with salt.