How to avoid lumps in béchamel (cold liquid into hot roux, or hot liquid into cold roux)
Combine opposite temperatures—cold milk into hot roux (or hot liquid into cold roux)—to get a smooth béchamel without lumps.
The chef explains adding cold milk to hot roux causes rapid expansion and a smooth, luxurious sauce rather than a lumpy one. He generalizes the rule as cold liquid + hot roux, or hot liquid + cold roux.
The short version
- Use cold milk with hot roux (or hot liquid with cold roux) to prevent lumps
What goes wrong
Adding hot liquid to hot roux and getting lumps
Use opposite temperatures: cold liquid + hot roux, or hot liquid + cold roux.
Why it works
Opposite temperatures help disperse starch and hydrate it evenly, reducing clumping.
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