Making and Storing Roux (Technique Card)

The foundational French/Cajun thickening agent — fat + flour cooked together. Different cooking times = different colours = different uses. Make a batch and store; saves 10 min on every sauce, gravy, gumbo, jambalaya, mac & cheese, dauphinoise, béchamel.

Heat: 0/5.

Ratio

1:1 by weight — equal parts fat to flour. Standard yield: 1 cup roux per ½ cup butter + ½ cup flour (~115 g each).

Fat options

• Butter (classic French — for béchamel, velouté, white sauces)
• Vegetable oil / clarified butter (for darker Cajun roux — won’t burn at higher temps)
• Bacon grease / lard (for gravies and Southern cooking — adds savoury depth)
• Pan drippings (from a roast — best gravies)

The four colour stages

Colour	Cook time	Smell	Use
White	2-3 min	Just past raw flour; no toasting	Béchamel, mac & cheese, dauphinoise
Blond (peanut butter)	5-10 min	Lightly toasted	Velouté, chicken gravy, sauce suprême
Brown (caramel)	15-20 min	Nutty, caramel	Gumbo (some styles), beef gravy, Mushroom and Onion Gravy
Dark/Chocolate	30-45 min	Toasted-bread, almost coffee	Cajun gumbo, étouffée

⚠️ Darker roux = less thickening power. Dark roux thickens about ¼ as much as white. Use more roux for darker sauces.

Method (any colour)

1. Melt fat in a heavy, dry saucepan over medium-low (or medium for darker). Use cast iron for the darkest roux — won’t scorch as easily.
2. Add flour all at once. Whisk continuously until fully incorporated and smooth.
3. Cook to colour. Watch and smell; stir/whisk constantly. The change is gradual but accelerates near the end.
4. Done: for white/blond, pull at the colour. For brown/dark, pull just before the target colour — residual heat keeps cooking.
5. Use immediately OR cool + store.

Storage

• Fridge: scoop into a clean glass jar. Cap. Keeps 3 weeks.
• Freezer: scoop into ice-cube trays or muffin tin; freeze; pop into freezer bag. Each cube/portion is 1 sauce-worth. Keeps 6 months.
• From frozen: drop frozen cube directly into simmering liquid; whisk to dissolve.

Using roux (the universal rule)

To thicken a sauce / gravy / soup:

• For each 1 cup hot liquid (broth, milk, cream), use 2 tbsp roux for medium-thick.
• Add roux to hot liquid (not cold) — whisking vigorously. Don’t dump cold roux in cold liquid (lumps).
• Or add cold liquid to hot roux. Whichever way, whisk to smooth before more liquid.
• Simmer 2-3 min after combining to cook out flour taste.

Use with existing cards

• Dauphinoise potatoes — no roux (cream-only base), but a white roux makes the cheese topping richer.
• Mushroom and Onion Gravy (cogumelo_mushroom-onion-gravy.md) — brown roux is the base.
• Welsh rarebit (queijo-cheddar_welsh-rarebit.md) — white roux thickens the beer base.
• Mac and Cheese (nhoque_baked-mac-and-cheese.md) — white-blond roux for the cheese sauce.
• Moussaka (carne-moida_moussaka-hairy-biker.md) — white roux for the béchamel topping.
• Coq au vin (frango-coxa_coq-au-vin.md) — light roux thickens the wine reduction.

Notes

• Don’t walk away from a darkening roux. The 5-7 min mark is OK to step away; from minute 15 onward, you stay at the stove.
• Burnt roux is irreversible. Black specks = throw it out, start over.
• Cast iron is the traditional Cajun pan for very dark roux — its mass evens the heat.
• Whole-grain flour doesn’t work; the bran disrupts thickening. White all-purpose / farinha de trigo branca.
• Gluten-free roux: use Bob’s Red Mill GF flour 1-to-1 or cornstarch slurry (different technique).