Roasted Beef Tenderloin with French Onions

This roasted beef tenderloin with French onions is a luxurious, melt-in-the-mouth main dish that’s perfect for holiday dinners, special occasions, or when I just want to treat myself and guests to something unforgettable. The tenderloin is perfectly roasted to a rosy medium-rare, and the rich, caramelized French onions take it to a whole new level of depth and flavor.

Why You’ll Love This Recipe

I love how this dish combines elegance and comfort. The beef tenderloin turns out incredibly juicy and tender, while the deeply savory French onions add richness and complexity. Even though it looks and tastes like a restaurant-quality meal, I find it surprisingly straightforward to make at home with the right steps. It’s a showstopper that always impresses and satisfies.

Ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

• Beef tenderloin roast (center-cut, trimmed)

• Kosher salt and black pepper

• Olive oil or neutral cooking oil

• Fresh garlic, minced

• Fresh thyme or rosemary

• Butter

• Yellow onions, thinly sliced

• Beef broth or stock

• Balsamic vinegar or dry sherry (optional, for added depth)

Directions

1. I start by seasoning the beef tenderloin generously with salt and pepper, rubbing it in evenly. I let it sit at room temperature for about 30–45 minutes to ensure even cooking.

2. In a large skillet or roasting pan, I sear the tenderloin in hot oil on all sides until it’s beautifully browned. This step locks in the juices and builds flavor.

3. After searing, I transfer it to a wire rack in a roasting pan and roast it in a preheated oven at 425°F (220°C) for about 25–35 minutes, depending on the desired doneness. I always use a meat thermometer—125°F (52°C) for medium-rare.

4. While the beef roasts, I make the French onions. I slowly cook sliced onions in butter over low heat, stirring often, until they’re golden and caramelized—this takes about 30–40 minutes.

5. Once caramelized, I deglaze the pan with a splash of balsamic vinegar or sherry, then add beef broth and let it reduce slightly. The result is a silky, savory onion topping packed with umami.

6. I let the beef rest for 10–15 minutes after roasting before slicing it. I serve it with a generous spoonful of the French onions over the top.

Servings and timing

This recipe serves 6 to 8 people, depending on portion size. Prep time is about 20 minutes, cook time is 40–50 minutes (including the onions), and resting time for the beef is 10–15 minutes. Total time: roughly 1 hour 15 minutes.

Variations

Sometimes I rub the tenderloin with a garlic-herb butter before roasting to add more flavor. I’ve also topped it with a red wine reduction or mushroom sauce instead of onions for a different take. For a bolder twist, I’ll mix Dijon mustard into the seasoning rub, or use shallots instead of yellow onions for a more delicate, sweet onion flavor.

Storage/Reheating

I store leftover beef in an airtight container in the refrigerator for up to 3 days. To reheat, I slice it thin and warm it gently in a skillet with a splash of broth or cover it and reheat in the oven at a low temperature (around 275°F/135°C) to avoid drying it out. The onions keep well in the fridge too and can be reheated in a saucepan or microwave.

FAQs

How do I keep the beef tenderloin from drying out?

I always let the meat rest before slicing and never overcook it. Using a meat thermometer helps guarantee perfect doneness without guessing.

Can I make this ahead of time?

Yes, I often prepare the onions ahead and store them in the fridge. I also season the tenderloin ahead of time and keep it wrapped in the fridge until ready to sear and roast.

What side dishes pair best with this?

I like to serve it with creamy mashed potatoes, roasted vegetables, or a crisp green salad. Anything that can soak up the juices and onions works beautifully.

Can I use a different cut of beef?

This recipe is tailored for tenderloin because of its tenderness and quick cooking time, but it can also work with sirloin roast or ribeye roast—though the cooking times will vary.

What’s the best way to slice the tenderloin?

I use a sharp carving knife and slice it across the grain into thick medallions for the most tender bites.

Conclusion

Roasted beef tenderloin with French onions is one of those recipes I turn to when I want to create something truly special. It’s rich, flavorful, and beautifully balanced. Whether it’s for a dinner party, holiday meal, or a cozy weekend treat, this dish never fails to impress—and it’s easier to make than it looks.

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