Chateaubriand sauce béarnaise

Take the chill off the beef. Leave the 450 g centre-cut tenderloin out only long enough to lose its refrigerator chill, then pat dry. Heat: room temperature. Timing: 20 minutes passive rest. Purpose: A short tempering period improves surface browning without prolonged room-temperature holding. The exterior no longer feels refrigerator-cold and is completely dry before searing. Safety. Do not exceed a 2-hour cumulative room-temperature limit.

Make the tarragon reduction. Simmer the vinegar with shallot, crushed peppercorns and tarragon stems until about 15 ml liquid remains; strain. Heat: medium-low. Timing: 10 minutes. Purpose: A concentrated acidic reduction supplies the classic béarnaise backbone. The reduction is sharply aromatic and only about 15 ml liquid remains after straining.

Build the yolk foam. Whisk the 40 g pasteurized yolks with the reduction and 15 ml water over gentle heat until thick and foamy, keeping the mixture between 55 and 60 °C. Heat: gentle indirect heat. Timing: 5 minutes. Target: 55–60 °C. Purpose: Controlled heat thickens the emulsion base without scrambling the yolks. The whisk leaves visible trails and the yolk mixture is thick enough to mound briefly. Safety. Use pasteurized yolks because this sauce is held below a full egg-cooking safety endpoint.

Emulsify the butter. Remove the bowl from direct heat and whisk in the 90 g clarified butter gradually, then add chopped tarragon and 1 g salt. Timing: 5 minutes. Purpose: Slow butter addition stabilises the warm emulsion. The sauce is glossy, spoonable and holds together without oily pools. Safety. Keep warm, not hot; do not reheat aggressively.

Sear the tenderloin. Season the beef with 5 g salt and pepper, heat the 10 g oil, and sear all broad surfaces until deeply browned. Heat: high. Timing: 6 minutes. Purpose: Fast browning builds flavour before the centre overcooks. The exterior has an even mahogany-brown crust without burnt patches. Safety. Use tongs rather than piercing the meat.

Finish in the oven. Transfer the skillet to a 180 °C oven and roast until the centre reaches 63 °C. Heat: 180 °C oven. Timing: 8 minutes. Purpose: Thermometer control is more reliable than timing alone for a thick centre cut. The centre reaches 63 °C on an instant-read thermometer while the exterior remains well browned. Safety. Measure in the geometric centre of the beef.

Rest and carve. Rest the beef before slicing it across the grain into thick pieces. Timing: 5 minutes passive rest. Purpose: The safety guidance for whole beef includes at least a 3-minute rest after 63 °C. Juices remain mostly in the meat when it is carved and the slices stay moist. Safety. Rest for at least 3 minutes before carving.

Sauce and serve. Spoon the béarnaise alongside the sliced beef and serve immediately. Heat: warm. Timing: 2 minutes. Purpose: Serving the sauce alongside preserves both crust and emulsion texture. The beef is hot and juicy, and the béarnaise remains glossy rather than split. Safety. Discard béarnaise that has stood at room temperature for more than 2 hours.