This grilled tenderloin sandwich is the ultimate steak sandwich: tender, juicy beef fillet seasoned simply, grilled to a perfect medium-rare, and piled onto crusty bread with caramelized onions and a horseradish cream. It works because the lean tenderloin is cooked quickly over high heat, keeping it moist and flavorful, while the creamy sauce and sweet onions balance the rich meat. This is a restaurant-quality sandwich you can easily make at home for a special lunch or casual dinner.
Ingredients
- 1 lb (450 g) beef tenderloin, trimmed of silver skin
- 2 tbsp (30 ml) olive oil
- 1 tsp kosher salt
- 1/2 tsp freshly ground black pepper
- 2 large yellow onions, thinly sliced (about 3 cups / 300 g)
- 1 tbsp (15 g) butter
- 1/2 cup (120 ml) beef broth
- 1 tbsp (15 ml) Worcestershire sauce
- 4 crusty sandwich rolls (e.g., ciabatta, baguette, or hoagie)
- 1/2 cup (120 g) sour cream
- 2 tbsp (30 g) prepared horseradish
- 1 tbsp (15 ml) Dijon mustard
- 1 tbsp (15 ml) fresh lemon juice
- 2 cloves garlic, minced
- Fresh arugula or baby spinach (optional, for serving)
Instructions
- Take the beef tenderloin out of the refrigerator 30 minutes before cooking to let it come to room temperature. Pat it dry with paper towels.
- While the beef rests, make the horseradish cream: in a small bowl, stir together the sour cream, horseradish, Dijon mustard, lemon juice, and minced garlic. Season with a pinch of salt and pepper. Cover and refrigerate until ready to use.
- Preheat a grill (gas or charcoal) to high heat, about 450–500°F (230–260°C). If using a grill pan, heat it over high heat for 2 minutes.
- Rub the tenderloin all over with 1 tablespoon of the olive oil, then season generously with the kosher salt and black pepper.
- Grill the tenderloin for 4–5 minutes per side for medium-rare, or until an instant-read thermometer inserted into the thickest part registers 130°F (54°C) for medium-rare. For medium, cook to 135°F (57°C). Remember: the USDA FSIS safe minimum for whole cuts of beef is 145°F (63°C) with a 3-minute rest, but if you prefer a more done steak, cook to that temperature.
- Transfer the beef to a cutting board and let it rest for 10 minutes. This allows the juices to redistribute.
- While the beef rests, heat the remaining 1 tablespoon olive oil and the butter in a large skillet over medium heat. Add the sliced onions and cook, stirring occasionally, until soft and golden brown, about 10 minutes. If they start to stick, add a splash of water.
- Add the beef broth and Worcestershire sauce to the onions, scraping up any browned bits. Simmer for 2–3 minutes until slightly thickened. Season with salt and pepper to taste.
- Slice the rested tenderloin thinly against the grain, into 1/4-inch (6 mm) slices.
- Split the sandwich rolls and toast them on the grill or under a broiler until lightly golden.
- Spread a generous layer of horseradish cream on the bottom half of each roll. Top with sliced beef, then a pile of caramelized onions. Add a handful of arugula if using, and close the sandwich.
- Serve immediately, with extra horseradish cream on the side.
Tips
- Don’t skip the rest: Letting the cooked tenderloin rest for at least 10 minutes is crucial. If you slice it immediately, the juices will run out and leave the meat dry.
- Use a meat thermometer: Tenderloin is lean and can go from perfect to overcooked in a minute. A thermometer takes the guesswork out. For medium-rare, pull it at 130°F (54°C) because carryover cooking will raise it to about 135°F (57°C) during the rest.
- Slice against the grain: Look at the muscle fibers in the cooked meat and slice perpendicular to them. This shortens the fibers and makes each bite more tender.
- Substitutions: If you can’t find beef tenderloin, use sirloin or flank steak, but adjust cooking time – sirloin may need a bit longer, flank steak is best cooked to medium-rare and sliced thinly.
Serving Suggestions
Serve this sandwich with crispy French fries, a simple green salad, or grilled vegetables. It also pairs well with a cold beer or a glass of full-bodied red wine like Cabernet Sauvignon. For a complete meal, add a side of pickles or coleslaw.
Variations
- Cheesy version: Add a slice of provolone or Swiss cheese to the bottom half of the roll before adding the beef, then briefly toast under the broiler until melted.
- Spicy kick: Add a few slices of jalapeño or a drizzle of sriracha to the horseradish cream.
- Mushroom version: Sauté 8 oz (225 g) sliced mushrooms with the onions for an earthy flavor.
- Herb crust: Rub the tenderloin with a mixture of minced rosemary, thyme, and garlic before grilling.
Storage and Reheating
Store leftover sliced beef and onions separately from the bread and sauce in airtight containers. Refrigerate within 2 hours of cooking. The beef and onions will keep for up to 3 days. To reheat, warm the beef and onions in a skillet over medium heat with a splash of beef broth until heated through (165°F / 74°C for leftovers). Do not microwave the beef, as it will become tough. Assemble fresh sandwiches with reheated filling and fresh bread. The horseradish cream can be refrigerated for up to 5 days.
Frequently Asked Questions
Can I use a different cut of beef? Yes, sirloin or ribeye work well. Ribeye is fattier and more forgiving; sirloin is leaner and benefits from marinating. Adjust cooking time based on thickness.
Can I cook this indoors without a grill? Absolutely. Use a cast-iron skillet or grill pan over high heat. Sear the beef for the same time, and you’ll get a nice crust.
What is the best bread for this sandwich? A crusty roll that can hold up to the juicy filling is best. Ciabatta, a baguette, or a sturdy hoagie roll all work well. Avoid soft bread that will get soggy.
How do I know when the tenderloin is done? Use an instant-read thermometer. For medium-rare, it should read 130°F (54°C) before resting. For medium, 135°F (57°C). For well-done, 145°F (63°C) or higher, but note that tenderloin will be dry beyond medium.
Can I prepare the horseradish cream ahead of time? Yes, you can make it up to 2 days in advance and keep it refrigerated. Stir well before using.
Can I freeze the cooked beef? Yes, sliced beef can be frozen in an airtight container for up to 2 months. Thaw overnight in the fridge and reheat gently in a skillet with a little broth to prevent drying out.
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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes
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