Mushroom & Caramelized Onion Stuffed Beef Tenderloin

1 h 45 min | intermediate | high-protein

Sliced stuffed beef tenderloin roast on a white platter, showing a spiral filling of mushrooms and caramelized onions. The roast is coated in glossy red wine pan sauce with extra mushrooms and onions spooned over and around it, garnished with herbs on a light tabletop.

Recipe by Eunice Published Aug 22, 2025

Prep Time	Cook Time	Total Time
30 min	1 h 15 min	1 h 45 min

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Introduction

This mushroom and caramelized onion stuffed beef tenderloin is an elegant centerpiece that feels straight out of a cozy steakhouse.

Rich Gruyère, sweet onions, and earthy mushrooms create a savory filling that keeps the beef juicy and full of flavor.

It is perfect for holidays, special date nights at home, or any dinner party where you want to really impress.

Close-up of a sliced beef tenderloin roulade stuffed with caramelized onions and mushrooms, served beside mashed potatoes and spooned with glossy red wine pan sauce.

How to Make Mushroom & Caramelized Onion Stuffed Beef Tenderloin

Prep mode (keeps screen active)

Prep the tenderloin and season

Preheat your oven to 400°F and set a rack in the center.
Stir the salt, pepper, and 2 teaspoons of the bouillon powder together in a small bowl.
Pat the beef dry, butterfly it lengthwise, and gently pound it to an even thickness.
Rub the seasoned bouillon mixture all over the inside of the tenderloin and let it sit while you cook.
Caramelize the onions

Heat the olive oil and butter in a large skillet over medium heat until the butter melts.
Add the sliced onions and a pinch of salt, then cook, stirring often, until deep golden and very soft.
Lower the heat if the onions brown too quickly, and plan for 25 to 30 minutes for full caramelization.

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Cook the mushrooms and make the filling

Stir the chopped mushrooms into the onions and cook until they release their liquid and start to brown.
Add the garlic, thyme, and remaining 1 teaspoon bouillon powder and cook just until fragrant, about one minute.
Take the pan off the heat, then stir in the breadcrumbs and Gruyère until evenly combined.
Let the filling cool until just warm so it is easier to spread on the tenderloin.
Fill, roll, and tie the roast

Lay the butterflied tenderloin open on a cutting board, cut side up, with the long side facing you.
Spread the mushroom and onion mixture evenly over the surface, leaving a 1 inch border on all sides.
Roll the beef up tightly from the long side into a log, tucking in any loose filling as you go.
Tie the rolled tenderloin with kitchen twine every 1 1/2 to 2 inches to hold the shape securely.
Transfer the roast to a plate and chill for 20 minutes while you clean the skillet and prepare to sear.
Sear and roast the tenderloin

Return the empty skillet to medium high heat and add a splash of oil if it looks dry.
Sear the stuffed tenderloin on all sides until nicely browned, about 2 to 3 minutes per side.
Move the seared tenderloin to a rimmed baking sheet or oven safe skillet, placing it seam side down.
Roast until the center reaches 125°F for medium rare or 135°F for medium, about 20 to 30 minutes.
Transfer the roast to a cutting board, tent loosely with foil, and let rest at least 15 minutes.

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Make the red wine pan sauce

Place the searing skillet back over medium heat and pour in the red wine, scraping up browned bits.
Let the wine simmer until reduced by about half, then add the beef stock and any resting juices.
Continue to simmer until slightly thickened and glossy, 8 to 10 minutes, then taste and adjust seasoning as needed.
Strain the sauce through a fine mesh sieve if you prefer a smoother texture, or serve it rustic from the pan.
Slice and serve

Remove the kitchen twine from the rested tenderloin and slice it into thick rounds with a sharp knife.
Arrange the slices on a warm platter and spoon the red wine sauce generously over the top.

Slice of mushroom and caramelized onion stuffed beef tenderloin on a white plate, served with a mound of mashed potatoes and drizzled with red wine pan sauce; extra sautéed mushrooms and onions scattered around.

Substitutions

Gruyère cheese -> Fontina or provolone cheese: Fontina or provolone melt just as beautifully as Gruyère and give the filling a slightly milder, ultra creamy flavor.
Cremini mushrooms -> Mixed wild mushrooms: Shiitake, oyster, or chopped portobello mushrooms add deeper earthiness and a meaty bite that stands out against the tender beef.
Dry red wine -> Port wine: Port wine creates a richer, slightly sweet sauce that feels very restaurant worthy and pairs beautifully with the savory stuffing.

Close-up of a thick slice of mushroom and caramelized onion–stuffed beef tenderloin, pink in the center, plated on creamy mashed potatoes with sautéed mushroom slices and red wine pan sauce, garnished with a few thyme leaves.

Tips

Butterfly with control, not speed: Use a long sharp knife and take shallow cuts as you open the tenderloin so you do not accidentally pierce through.
Caramelize, do not rush the onions: If the onions start to scorch, add a tablespoon of water, scrape the pan, and lower the heat slightly.
Keep the filling from squeezing out: Leave that clean border around the edges and roll gently but firmly so the filling has space and stays inside.
Trust an instant read thermometer: Insert the probe into the very center of the roast from the side so you hit the thickest part.
Use the resting time wisely: Make the pan sauce while the meat rests so the juices have time to redistribute and your timing stays stress free.
Warm plates for serving: Serve on warm plates or a warmed platter so the sauce does not cool and thicken before everyone sits down.

Nutrition Facts ^*

Energy	476	kcal
Protein	44	g
Total Fat	25	g
Carbohydrates	10	g
Dietary Fiber	2	g

^* Approximate, per serving.
Data source: USDA FoodData Central.

Sliced mushroom and caramelized onion–stuffed beef tenderloin on a white platter, topped with glossy red wine pan sauce and sautéed onions and mushrooms.

FAQ

What if my stuffing keeps squeezing out while I roll the tenderloin?: Cool the filling longer so it firms up slightly and is less slippery against the meat. Make sure you left that 1 inch border clean so the filling has room when you start rolling. If needed, scoop any escaped filling back in from the sides before tying with twine.
How do I avoid overcooking the beef tenderloin?: Start checking the temperature a little earlier than you think, especially if your tenderloin is on the smaller side. Pull it from the oven at 5°F below your target because the temperature will rise as it rests. Avoid cutting into the roast early, since that releases hot juices and slows down gentle carryover cooking.
Can I make this recipe without wine or alcohol?: Yes, you can use extra beef stock with a tablespoon of balsamic vinegar for brightness instead of the red wine. Let the stock mixture reduce a little longer so the flavor is concentrated and the sauce still tastes rich.
Can I stuff the tenderloin ahead of time?: Yes, you can assemble, roll, and tie the roast up to one day ahead. Wrap it tightly in plastic, refrigerate, then bring it out 45 minutes before searing so it is not ice cold. Plan for a few extra minutes in the oven if it is starting colder.
How should I reheat leftovers without drying out the meat?: Slice the leftover tenderloin and place it in a baking dish with a splash of stock or leftover sauce. Cover tightly with foil and warm in a 275°F oven just until hot, about 10 to 15 minutes. Avoid microwaving on high, which can turn the meat gray and tough around the edges.