Béarnaise — Reduction, Sabayon, Mounting

Béarnaise is a classical French emulsified butter sauce closely related to hollandaise but distinctly different in its reduction base, aromatics, and intended application. Where hollandaise uses a simple wine and vinegar reduction, béarnaise is built on a tarragon and shallot reduction with white wine and tarragon vinegar that gives the sauce its characteristic anise-forward, herbaceous, slightly acidic depth that pairs specifically with grilled red meat, particularly entrecôte. The production follows three sequential stages: reduction, sabayon, and mounting. The reduction — shallots, fresh tarragon stems (not leaves), black peppercorns, white wine, and tarragon vinegar — is simmered until approximately 2 tablespoons of highly concentrated, aromatic liquid remain. This reduction is the flavour engine of the sauce; insufficient reduction produces a flat, watery béarnaise regardless of butter quality or technique. The reduced liquid is strained or left unstrained (classical debate exists on both sides) and the egg yolks are added. The yolks are cooked to a sabayon over a bain-marie as in hollandaise — whisked continuously at 60–65°C until thick, ribbon-dropping, and pale. This represents the critical moment where the proteins are partially denatured into their emulsifying configuration without scrambling. Warm clarified butter is then mounted gradually into the sabayon — initially drop by drop until the emulsion establishes, then in a thin, steady stream. At completion, freshly chopped tarragon leaves and optionally chervil are folded in — these are added after mounting because their volatile aromatic compounds are destroyed by the heat of the mounting process if added earlier. The distinction from hollandaise is not merely the reduction but the final flavour — béarnaise is assertive, herbaceous, and anise-forward in ways that make it inseparable from grilled beef in classical French cuisine.