One 3- to 5-pound beef tenderloin, trimmed

 1/4 cup extra-virgin olive oil 

Kosher salt and freshly ground black pepper

5 sprigs fresh thyme 

3 cloves garlic, crushed 

5 tablespoons unsalted butter, at room temperature 

1 medium shallot, minced 

1 cup red wine 

2 cups beef stock 

1 tablespoon all-purpose flour 

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1. Bring to Room Temperature: Remove the tenderloin from the refrigerator 1 hour before cooking to allow it to come to room temperature.

2. Prepare and Tie the Tenderloin: On the tapered tail end of the tenderloin (about one-third from the end), make an incision almost all the way through. Fold the tail underneath to create an even cylinder. Tie the tenderloin crosswise every ¾ to 1 inch using ten to twelve 8-inch pieces of butcher’s twine. This ensures even cooking and a uniform shape. Preheat the oven to 225°F.

3. Sear the Beef: Pat the tenderloin dry. Brush with 1 tablespoon of the olive oil and season generously with salt and pepper on all sides.

4. In a cast-iron pan over medium-high heat, add the remaining 3 tablespoons olive oil. When hot, sear the beef on all sides until a golden crust forms, about 1–2 minutes per side. Add the thyme, garlic, and 3 tablespoons of the butter. Once the butter melts, baste the beef with the herb- and garlic-infused butter for 30 seconds.

5. Roast the Tenderloin: Transfer the beef to a rack on a baking sheet. Spoon 2 tablespoons of the herb and garlic butter from the pan over the tenderloin (reserve the pan with the remaining contents). Roast in the oven until the internal temperature of the thickest part reaches 120°F for medium-rare, about 1 to 2 hours depending on size. Remove from the oven, cover loosely with foil, and let rest for 15 minutes.

6. Make the Pan Sauce: Place the reserved cast-iron pan over medium heat. Add the minced shallots and cook until translucent, 3–5 minutes. Deglaze the pan with red wine, scraping up any brown bits, and reduce until nearly dry, about 5–8 minutes. Add the beef stock, bring to a simmer, and reduce by half, 10–15 minutes.

7. Finish the Sauce: In a small bowl, mix the remaining 2 tablespoons butter with the flour to form a paste (beurre manié). Reduce the heat to low and whisk the paste into the sauce gradually, until it reaches your desired consistency. Adjust seasoning if needed.

8. Serve: Slice the rested tenderloin and serve with the red wine pan sauce.

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