Beef fillet with Béarnaise mayonnaise

Ingredients:

• 1 whole beef tenderloin weighing 2-2.5 kg, trimmed and tied with string
• 80 g unsalted butter, melted
• 3/4 cup chopped shallots (3 pcs.)
• 4 tablespoons chopped fresh tarragon leaves
• 0.5 cups dry white wine
• 1/4 cup tarragon or white wine vinegar
• 3 large egg yolks at room temperature
• 3 tablespoons freshly squeezed lemon juice at room temperature
• 1 tbsp Dijon mustard
• 1 cup of vegetable oil at room temperature
• 0.5 cups of quality olive oil at room temperature
• Special equipment: zester

Preparation:

1. Preheat oven to 135°C. Line a baking sheet with foil.
2. Pat the beef tenderloin dry with paper towels and brush the top and bottom with butter. Sprinkle with 4 teaspoons of salt and 2 teaspoons of black pepper. It may seem like a lot of salt, but trust me, it's important.
3. Place the fillet on a baking sheet and roast for 1 hour to 1 hour 15 minutes, or until a thermometer inserted into the end of the fillet registers 135°F (54°C) for medium-rare. Remove the meat from the oven, cover tightly with foil, and let it rest at room temperature for 15 minutes. Remove the foil and let the meat sit at room temperature.
4. Meanwhile, combine the shallots, 3 tablespoons of tarragon, wine, and vinegar in a small saucepan and bring to a boil over medium heat. Cook for 5 minutes, until the liquid has reduced to 1 cup. Let cool for 15 minutes.
5. Place the egg yolks, lemon juice, mustard, 2.5 teaspoons of salt, and 1 teaspoon of black pepper in the bowl of a food processor and pulse for 10 seconds. With the processor running, slowly pour in the vegetable and olive oils until a thick emulsion forms. Add the chopped shallots and remaining tarragon and pulse. Refrigerate the sauce until ready to serve.
6. Cut the beef into 0.5-1 cm thick slices, sprinkle with salt and serve warm or chilled with Béarnaise mayonnaise.