Prep the Tenderloin:
Let the beef come to room temperature (30–45 minutes). Preheat oven to 450°F (230°C). Combine olive oil, garlic, rosemary, thyme, salt, and pepper. Rub the tenderloin with Dijon mustard (if using), then with the herb mixture.
Sear the Beef:
In a large skillet over high heat, sear the tenderloin on all sides (2–3 minutes per side) until nicely browned.
Roast:
Transfer tenderloin to a rack on a baking sheet or roasting pan. Roast for 35–45 minutes, until internal temperature reaches:
120–125°F for rare
130–135°F for medium-rare
140–145°F for medium
Rest the Beef:
Remove from oven, tent with foil, and rest for 15–20 minutes before slicing.
Make the Red Wine Sauce:
In a saucepan, melt 1 tablespoon butter over medium heat. Add shallots and garlic; sauté 2–3 minutes. Pour in wine, broth, balsamic vinegar, and thyme. Simmer until reduced by half (10–15 minutes). Remove from heat and whisk in 2 tablespoons cold butter to finish. Season with salt and pepper.
Slice & Serve:
Slice the rested beef tenderloin into ½–1 inch slices. Spoon red wine sauce over each portion.