The Roux and the Mother Sauces: A Calculator for Better Sauces

Half the sauces in classical cooking start the same way: a roux — equal parts butter and flour, cooked together, then thickened with liquid. It sounds dull and looks like paste, but the roux is a small chemical factory: the flour's starches absorb liquid and swell, turning milk or stock into béchamel or velouté. Master the roux and you can make a dozen sauces without a recipe, because they're all the same two ingredients at different ratios and colors.

The ratio: equal parts by weight

Roux is 1:1 butter to flour by weight — 14 g of each (one generous tablespoon of butter and about two of flour) thickens roughly 250 ml of liquid to a medium sauce. Scale from there:

• Thin (soups, light sauces): about half that — 7 g each per 250 ml.
• Medium (béchamel, velouté): 14 g each per 250 ml.
• Thick (croquettes, soufflé base): double — 28 g each per 250 ml.

Try it — set the thickness, volume, and roux color:

Color is flavor — and it costs thickening power

The longer a roux cooks, the darker and more flavorful it gets — and the less it thickens, because browning breaks down the starches. Four standard stages:

• White roux (2–3 min): maximum thickening, neutral flavor. Béchamel, velouté, cream sauces.
• Blond roux (5–7 min): still strong thickening, a light toasty note. Cheese sauces, pale gravy.
• Peanut roux (8–12 min): nutty flavor, noticeably less thickening. Espagnole, brown sauces.
• Brown roux (15–20 min): deep flavor, little thickening. Gumbo and Cajun cooking — which is why gumbo uses a lot of it.

The five mother sauces

Classical French cooking organizes every sauce under five "mothers": béchamel (roux + milk), velouté (roux + light stock), espagnole (brown roux + brown stock + tomato), tomato (tomato + aromatics), and hollandaise (the odd one out — an emulsion of butter and egg yolk, no roux). From the first four, add flavor and you get daughters: cheese into béchamel, mushrooms and cream into velouté, wine into espagnole. Learn the mothers and you have inherited a sauce system, not a recipe list.

Technique: the three things that go wrong

1. Cold liquid into hot roux = lumps. Whisk in warm liquid gradually, off the heat first, then return to heat. (Or the reverse: warm roux into cold liquid — but not cold into hot.)
2. Rushing the flour. Cook the roux until the raw flour taste is gone — about 2 minutes minimum. A white roux should smell like toasted pastry, not raw dough.
3. Losing the season. A roux sauce is blank canvas — salt, white pepper, and nutmeg for béchamel; the stock carries velouté. Season at the end, taste, and trust your tongue over the recipe.

The key takeaway: roux is equal parts butter and flour by weight, cooked to the color your sauce needs, and thickened with warm liquid whisked in gradually. The four mothers are the same roux plus milk, stock, tomatoes, or time.

Great pan sauces follow the same logic one step further — the pan sauce guide turns browned bits into dinner. And because stock quality decides velouté, stock vs broth is the companion piece.