Equal weights of fat and flour cooked together, from a pale blond through to a dark chocolate brown. It is the foundation of béchamel, velouté, gumbo and most classical gravies.
What it does in a recipe: Lump-free flour thickening plus whatever flavour the fat and the browning contribute. Pick the swap that covers that job — the ratios below are written so you can act on them without doing any arithmetic.
Also called: Flour and butter paste, Beurre manié (uncooked version)
4substitutes
2close matches
Thickenerscategory
Quick answer
Cornstarch slurry
2 tbsp butter + 2 tbsp flour (thickens 1 cup liquid) = 1 tbsp cornstarch mixed with 2 tbsp cold water
All substitutes, best first
4 ways to replace roux
Cornstarch slurry
Reliable
2 tbsp butter + 2 tbsp flour (thickens 1 cup liquid) = 1 tbsp cornstarch mixed with 2 tbsp cold water
Cornstarch does the thickening job alone at about half the flour weight and needs no fat to keep it lump-free, since the cold slurry separates the granules instead.
MethodWhisk it into simmering liquid and cook for a minute, then stop.
Trade-offYou lose everything the roux brought besides thickening — the butter's richness and the toasted flour flavour that gives a gumbo or an étouffée its character. Glossy rather than velvety.
2 tbsp butter + 2 tbsp flour cooked = 2 tbsp butter + 2 tbsp flour kneaded together raw
The same ingredients in the same proportion, with the fat coating the flour to prevent lumps — the difference is that it is whisked into hot liquid uncooked rather than cooked first in the pan.
MethodWhisk small pinches into simmering liquid and let it bubble for two or three minutes to cook the flour out.
Trade-offNo toasted flavour at all, since the flour never browns, and it needs those extra minutes of simmering or the sauce tastes raw. Excellent for adjusting the thickness of a sauce at the last moment.
The fat's only structural job is to coat the flour particles, and oil does that as well as butter — it also has no milk solids to burn, so it can be taken to a much darker colour.
MethodThis is the standard approach for a dark Cajun roux, which needs 20 minutes or more of constant stirring to reach a deep brown.
Trade-offCleaner and less rich than butter, and the sauce lacks the dairy roundness a béchamel depends on.
Allergen checkThis is the dairy-free version, but it still contains wheat. If gluten is the issue, a starch slurry or a gluten-free flour blend is the route, not this.
Sweet rice flour in particular makes a smooth, stable roux that behaves close to a wheat one, since it is high in the amylopectin starch that gives a silky rather than grainy set.
MethodCook it for the usual couple of minutes; sweet rice flour browns more slowly, so judge by smell rather than colour.
Trade-offSlightly softer set and it will not take a dark Cajun roux well. Some blends leave a faint graininess.
Allergen checkSweet rice flour is reliably gluten-free, but ready-made GF blends may contain soy, nut flours or xanthan gum, and some are milled alongside wheat. Read the bag if the reason is coeliac disease rather than preference.
Worth knowing
The rule is equal weights of fat and flour, and roughly 2 tbsp of each thickens 1 cup of liquid to a medium sauce — halve that for a thin soup, double it for a thick binding sauce. The darker you take a roux the better it tastes and the less it thickens, so a dark gumbo roux needs considerably more than a blond one for the same body.
Cooking around an allergy? Diet tags here describe the ingredient itself, not any particular brand. Processed products change formulation without notice and shared production lines are common, so read the label on everything you use. A severe allergy is a medical matter — confirm with the manufacturer or your clinician rather than relying on a substitution chart.