Put the garlic into the chopping bowl with a pinch of salt (this helps to break it up) and pepper, then whizz until finely pulped—this is important as you do not want garlic chippings in the aïoli. Add the egg yolks, let them meet the garlic for a moment, then carefully and slowly add the oil in a gentle stream. The emulsion should safely hold up to 2 cups oil; at this point take a view and, if you can, add a little more oil. Now add the lemon juice, tasting as you go, adjust the seasoning, then refrigerate.