Roasted Beef Tenderloin with French Onions and Horseradish Sauce Recipe

Name: Roasted Beef Tenderloin with French Onions and Horseradish Sauce
Prep time: 1 h 45 min
Cook time: 30 min
Total time: 2 h 15 min
Cuisine: American
Ingredients: – 3 pounds trimmed whole beef tenderloin; – 2.5 pounds thinly sliced onions; – 6 ounces mayonnaise; – 6 ounces sour cream; – 3 ounces prepared horseradish; – 3 tablespoons butter; – Olive oil as needed; – 1 tablespoon kosher salt; – 1 tablespoon granulated garlic; – 2 teaspoons freshly cracked black pepper; – Juice and zest of half a lemon; – 2 large fresh thyme sprigs; – 2 large fresh rosemary sprigs; – 1 bay leaf; – 1/4 cup sherry wine; – Fresh thyme leaves for garnish

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Why You’ll Love This Roasted Beef Tenderloin with French Onions and Horseradish Sauce

Ease of preparation: This roasted beef tenderloin with French onions and horseradish sauce recipe is designed for simplicity, utilizing minimal ingredients and clear, straightforward steps that fit easily into a busy schedule. The overall cooking time ensures you can serve a gourmet centerpiece in about an hour and a half without stress.
Health benefits: The lean protein-packed beef tenderloin supports muscle health and fullness, while the sweet caramelized French onions deliver antioxidants and vitamins. The horseradish sauce offers digestive benefits and anti-inflammatory properties, combining to make this dish both nourishing and indulgent.
Versatility: Easily adjusted for different dietary needs, this recipe permits swaps such as vegan plant-based proteins or dairy-free horseradish sauce versions. It also accommodates gluten-free diets when using certified ingredients, and low-calorie adaptations by reducing fats or serving with light sides.
Distinctive flavor: The melding of tender, juicy beef, rich caramelized French onions, and the sharp, spicy horseradish sauce creates a sophisticated and memorable flavor profile. Its combination of sweet, savory, and tangy elements makes it stand out from typical roast dinners.

Essential Ingredients for Roasted Beef Tenderloin with French Onions and Horseradish Sauce

3 pounds trimmed whole beef tenderloin – the juicy, tender main protein centerpiece
2.5 pounds thinly sliced onions (French onions) – for slow caramelization providing sweetness and depth
6 ounces mayonnaise – base for creamy horseradish sauce
6 ounces sour cream – adds tanginess and creaminess to horseradish sauce
3 ounces prepared horseradish – delivers spicy and sharp flavor
3 tablespoons butter – for sautéing onions adding richness
Olive oil as needed – used in searing, roasting, and onion caramelization
1 tablespoon kosher salt – for seasoning beef
1 tablespoon granulated garlic – imparts savory flavor to beef
2 teaspoons freshly cracked black pepper – seasoning for beef and onions
Juice and zest of half a lemon – brightens horseradish sauce flavor
2 large fresh thyme sprigs – herbaceous notes for onions
2 large fresh rosemary sprigs – aromatic flavor for onions
1 bay leaf – adds depth to French onion preparation
1/4 cup sherry wine – deglazes and enhances onion flavor
Fresh thyme leaves for garnish – for final visual and flavor touch

Special Dietary Options

Vegan: Substitute beef tenderloin with seitan or portobello mushrooms, and use vegan mayonnaise and sour cream alternatives for horseradish sauce.
Gluten-free: Use labeled gluten-free horseradish sauce and verify all added seasonings are gluten-free.
Low-calorie: Use reduced-fat sour cream and mayonnaise variants, and reduce butter and oil quantities while maintaining flavor.

How to Prepare the Perfect Roasted Beef Tenderloin with French Onions and Horseradish Sauce: Step-by-Step Guide

First Step: Preheat and Prepare Beef

Preheat your oven to 450°F (232°C). Trim any excess fat from the beef tenderloin and pat it dry with paper towels. Allow the beef to sit at room temperature for about 20 minutes to ensure even cooking.

Second Step: Sear the Beef

Heat olive oil in a hot skillet over medium-high heat. Sear the beef tenderloin on all sides for approximately 2-3 minutes per side until a golden crust forms. This locks in the juices and builds flavor. Remove from heat and place beef on a rack set over a sheet pan.

Third Step: Caramelize French Onions

In a large heavy-bottom skillet or pot, heat olive oil and butter over medium-high heat. Add thinly sliced onions, seasoning with kosher salt and freshly cracked black pepper. Cook, stirring frequently, for about 10 minutes. Lower heat to medium-low and add thyme sprigs, rosemary, and bay leaf. Continue cooking slowly until onions are deeply caramelized and tender, about 45 minutes, stirring often.

Fourth Step: Deglaze and Simmer Onions

Stir in the sherry wine and simmer for an additional 15 minutes, allowing the liquid to reduce and flavors to concentrate. Remove herb sprigs and bay leaf. Adjust seasoning with salt as necessary and keep onions warm.

Fifth Step: Season and Roast Beef

Mix kosher salt, granulated garlic, and freshly cracked black pepper. Rub this seasoning evenly over the seared beef tenderloin. Place in the preheated oven and roast for approximately 30 minutes or until internal temperature reaches 135°F (57°C) for medium-rare. Adjust roasting time based on your desired doneness.

Sixth Step: Prepare Horseradish Sauce

In a bowl, whisk together mayonnaise, sour cream, prepared horseradish, lemon zest, and lemon juice until smooth. Season with salt and black pepper to taste. Refrigerate until serving.

Final Step: Rest, Slice, and Serve

Remove the roasted beef tenderloin from the oven and tent loosely with foil. Let it rest for 15 minutes to redistribute juices. Slice beef into quarter-inch slices against the grain. Serve topped with caramelized French onions and a dollop of horseradish sauce. Garnish with fresh thyme leaves. For dietary adjustments, substitute components as needed, ensuring a perfect plate for all.

Serving tip: Pair this dish with roasted fingerling potatoes and asparagus tossed in lemon zest and butter for a complete festive meal.

Dietary Substitutions to Customize Your Roasted Beef Tenderloin with French Onions and Horseradish Sauce

Protein and Main Component Alternatives

Swap beef tenderloin with seitan, portobello mushrooms, or tempeh for vegan or vegetarian adaptations.
Grilled salmon or roasted pork loin can provide pescatarian or alternative meat options, maintaining rich texture.

Vegetable, Sauce, and Seasoning Modifications

Use shallots or leeks instead of French onions for a milder, delicate flavor.
Prepare dairy-free horseradish sauce with vegan mayonnaise and coconut yogurt for lactose intolerant or vegan diets.
Incorporate fresh herbs like rosemary or thyme directly in the sauce for added complexity.
Reduce salt or substitute with low-sodium alternatives to tailor to dietary sodium restrictions.

Mastering Roasted Beef Tenderloin with French Onions and Horseradish Sauce: Advanced Tips and Variations

Pro cooking techniques: Use a meat thermometer for precision doneness and rest the beef to retain juiciness. Slow caramelization of onions ensures deep, sweet flavor without bitterness.
Flavor variations: Add smoked paprika or prepare mustard-infused horseradish sauce for an added kick. Consider finishing with a drizzle of balsamic reduction for contrast.
Presentation tips: Slice the beef thinly against the grain and plate with generous caramelized onions and horseradish dollops over a wooden board or elegant platter, garnished with thyme sprigs.
Make-ahead options: Caramelize onions and prepare horseradish sauce one day ahead to simplify meal day steps and enhance melding flavors.

How to Store Roasted Beef Tenderloin with French Onions and Horseradish Sauce: Best Practices

Refrigeration: Store leftover beef, onions, and horseradish sauce separately in airtight containers for up to 3-4 days to preserve freshness and texture.

Freezing: Freeze cooked beef tightly wrapped in foil or freezer bags for up to 2-3 months. Freeze onions and sauce separately to maintain flavor integrity.

Reheating: Warm gently in an oven at low temperature, avoiding microwave reheating which can dry the beef. Reheat onions on stovetop, stirring occasionally.

Meal prep considerations: Portion components separately for batch cooking to maintain best quality and easy assembly for meals throughout the week.

FAQs: Frequently Asked Questions About Roasted Beef Tenderloin with French Onions and Horseradish Sauce

What ingredients do I need to make French onions for beef tenderloin?

To make French onions for roasted beef tenderloin, you will need olive oil, butter, thinly sliced onions, kosher salt, freshly cracked black pepper, fresh thyme sprigs, fresh rosemary sprigs, a bay leaf, and sherry wine. These ingredients help create a rich and caramelized onion topping that pairs well with the beef.

How do I make horseradish sauce to serve with roasted beef tenderloin?

Combine mayonnaise, sour cream, prepared horseradish, lemon zest, and lemon juice in a bowl. Whisk the mixture until smooth and season it with salt and black pepper to taste. Refrigerate the sauce for at least 30 minutes before serving to let the flavors meld together.

At what temperature and for how long should I roast beef tenderloin?

Preheat your oven to 450°F (232°C) and roast the beef tenderloin for about 30 minutes. Use a meat thermometer to check for an internal temperature of 135°F (57°C) for medium-rare. Rest the meat covered with foil for 15 minutes before slicing to retain juices.

Can I prepare the horseradish sauce and French onions ahead of time?

Yes, both the horseradish sauce and French onions can be made ahead. The sauce should be refrigerated in an airtight container for up to 2 days. The onions can be cooked in advance, stored in the fridge, and gently reheated on the stovetop before serving.

How long should I caramelize the onions for the best flavor?

Cook the sliced onions over medium-high heat with olive oil and butter for about 45 minutes until they become deeply browned and caramelized. Then, add the herbs and sherry wine and simmer for an additional 15 minutes to develop a rich, complex taste that complements the beef tenderloin.

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