Roasted Beef Tenderloin with French Onions and Horseradish Sauce
A show-stopping dish perfect for special meals, this roasted beef tenderloin is paired with sweet French onions and a zesty horseradish sauce for a delightful balance of flavors.
Ingredients
For the French Onions
- Olive oil, as needed For coating the pot
- 3 tablespoons butter
- 2 1/2 lbs thinly sliced onions
- Kosher salt, to taste
- Freshly cracked black pepper, to taste
- 2 large fresh thyme sprigs
- 2 large fresh rosemary sprigs
- 1/4 cup sherry wine
For the Horseradish Sauce
- 6 oz mayonnaise
- 6 oz sour cream
- 3 oz prepared horseradish
- 1/2 lemon zested and juiced
For the Roasted Beef Tenderloin
- 3 lbs trimmed whole beef tenderloin
- Olive oil, as needed For coating the beef
- 1 tablespoon kosher salt
- 1 tablespoon granulated garlic
- 2 teaspoons freshly cracked black pepper
- Fresh thyme leaves, to garnish
Instructions
Make the French Onions
- Heat a large pot over medium-high and add oil to coat the bottom and the butter.
- Add sliced onions, a big pinch of salt and cracked pepper, and cook for about 10 minutes, stirring often.
- Lower heat to medium-low, add thyme, rosemary, and bay leaf, and cook slowly until onions are caramelized, about 45 minutes, stirring now and then.
- Stir in sherry and simmer about 15 minutes. Remove herb sprigs and bay leaf. Adjust salt and keep warm.
Make the Horseradish Sauce
- Combine mayonnaise, sour cream, horseradish, lemon zest, and lemon juice in a bowl.
- Whisk until smooth. Season with salt and pepper.
- Chill the sauce until serving.
Prepare and Roast the Beef Tenderloin
- Preheat oven to 450°F (230°C). Place the beef on a rack on a sheet pan. Pat dry and let sit 20 minutes at room temperature.
- Drizzle with olive oil and rub to coat. Mix salt, granulated garlic, and black pepper and rub over beef.
- Roast about 30 minutes, until internal temp reaches 135°F for medium-rare.
- Remove and tent with foil. Rest 15 minutes.
Slice and Serve
- Slice into 1/4-inch pieces. Serve with French onions and horseradish sauce. Garnish with thyme.
Notes
Use a meat thermometer to check doneness so you do not overcook the tenderloin. Let the beef rest before slicing to keep it juicy. Caramelize onions slowly for the best sweet flavor.