Both Sarah and I love to eat breakfast (or "breakfast" if it's after noon) at Cora's. They have (among many other things) a bunch of unique breakfast dishes that include Hollandaise on combinations of eggs, vegetables, cheese, crepes and other delectable food items.
In an effort to save a few dollars, I thought I'd make my own variation at home. I've created several successful copy-cat dishes before: usually eggs, cheese and a green vegetable on an english muffin topped with pre-packaged Hollandaise sauce mix. On a tastiness scale of 1 to 10, they usually rank a 7.5 where the genuine Cora's meal would get an 8... So a fair alternative.
This morning, I didn't have a packet of Hollandaise lying around, so I spent about 45 minutes this morning researching and preparing to whisk one up from scratch. There are several recipes, all of which are nearly identical; Egg yolks, lemon juice, butter, salt and pepper prepared over simmering water to prevent over-cooking the egg yolks.
Three eggs and a lot of manual whisking later, I had a perfect Hollandaise! A thick and creamy light yellow sauce that looked just like the packet variant... Except it tastes very similar to mayonnaise.
I thought I'd failed, but wikipedia had an explanation for me. It had the same basic preparation method as the other recipes but critically, it had this sentence at the end: "The same method -- with no heat, replacing the butter with oil, and adding some ground mustard -- is used to make mayonnaise."
Real Hollandaise Sauce is basically mayonnaise!