There are benchmarks in any career. Skills you must master to be a better carpenter, teacher, candlestick maker, whatever.
In cooking, it's sauces. In my French-based culinary education, it's the Mother sauces. They're also called "leading sauces" but the former phrase tends to stick.
They are (taken right from On Cooking):
Mother/leading sauce Liquid Thickener
Bechamel milk roux
Veloute white stock roux
veal veloute veal stock roux
chicken veloute chicken stock roux
(sensing a trend????)
Espagnole (brown stock) brown stock (beef) roux
Tomato sauce tomato optional -- roux*
Hollandaise butter egg yolks
So, we know how to make tomato sauce and Espagnole (beef stock). Bechamel is the foundation of any good mac n cheese so I know you know how to make it.
Veloutes are very useful as silky-smooth sauces over meats. Yummy.
The mother sauces are also building blocks to other small sauces. Adding gruyere and parmesan to a Bechamel turns it into Sauce Mornay. Add shallots, wine, and tomatoes to an Espagnole to make a Sauce Chasseur (Hunters sauce).
But hollandaise is special. It's a delicious one-trick-pony. It has an unchanging flavor profile -- lush and buttery with a lemony finish and a smoothness that comes right from the egg yolks.
But it's also a minefield. If the beaten yolks cook over the water bath, you're screwed. So, you have to focus only on the hollandaise or it'll scramble or break (when the oils separate from the body of the sauce). But when done right and held properly, it's a sublime addition to slightly bitter things like asparagus. It's also pretty fantastic over a cheap fillet mignon or on Eggs Benedict.
4 egg yolks
1 Tbsp lemon juice
1/2 cup (1 stick) melted butter
In a stainless steel bowl, beat the egg yolks and lemon juice together until almost doubled in volume.
Melt the butter, set aside
Put the bowl of eggs over a water bath that is at poaching temp, about 180 degrees, with a few tiny bubbles. The bottom of the bowl can not touch the water.
Whisk the eggs/lemon mixture over heat. If the eggs begin to turn white or you see tendrils of cooked egg, pull the bowl from the heat and continue to whisk.
S-l-o-w-l-y add the butter, whisking consantly. It will thicken almost immediately. Add cayenne and salt and you have a perfect hollandaise. Hold warm or serve immediately.
The roommate brought home duck eggs so I made hollandaise with duck eggs rather than chicken eggs. That's why it' such a neon yellow color. The yolks are beautiful.
Spring in Portland is as beautiful as duck egg hollandaise.
* On last season's Top Chef (Texas), a Dallas chef, Dean Fearing, quizzed the contestants on the mother sauces. He was Shocked! Agast! that no one put a roux in their tomato sauce. Really??? Roux in tomato sauce?? I think not. Butter is OK but roux, not so. Tomato sauce has the natural thickeners in tomatoes to add body to the sauce. If you're using a roux, your not reducing the sauce enough. Pffft. Cook it right.