Sauce Béarnaise: The Emulsified Butter Sauce
Béarnaise — the warm butter emulsion sauce of the French tradition — is structurally similar to hollandaise but uses a reduction of tarragon, shallot, and white wine vinegar as the acid base (rather than lemon juice), producing a completely different aromatic character. The same technical requirements apply: the egg yolks must reach approximately 60°C for the proteins to partially denature and provide emulsifying capacity; the butter must be added slowly enough for each addition to emulsify before the next; the temperature must never exceed 65°C.
- **The reduction:** Shallots, tarragon stems (not leaves), white wine, and white wine vinegar reduced to 2–3 tablespoons. This reduction is the flavour foundation — it must be tasted and corrected before the eggs are added. - **The egg yolks:** Whisked with the reduction over a bain-marie until they form slow ribbons and increase visibly in volume — indicating sufficient protein denaturation for emulsification. - **The butter:** Clarified butter, added warm (not hot) — in a thin stream while whisking continuously. [VERIFY] Robuchon's clarified vs whole butter specification. - **The tarragon leaves:** Added at the very end, off heat — the volatile aromatic compounds in fresh tarragon are destroyed by sustained heat. The addition of fresh leaves at the end preserves the bright anise-herbal character.
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