June 28, 2026 · 40 min

Pan-Seared Beef Tenderloin with Creamy Garlic Mashed Potatoes and Lemon Brussels Sprouts

Side Dish40 min1069 cal / serving

Treat yourself to an elegant dinner that feels like a special occasion. This recipe features tender beef tenderloin filets, seared to perfection and topped with a luxurious rosemary-infused demi-glace sauce. On the side, creamy garlic mashed potatoes and bright, crispy roasted Brussels sprouts with lemon make for a complete, satisfying meal.

The key to this dish is building layers of flavor: a good sear on the beef, a quick pan sauce using the fond and simple but thoughtful sides. It’s easier than you think and the result is a plate that looks and tastes like it came from a fine dining restaurant.


Recipe details

Side Dish40 min1069 cal / serving2 servings

Nutrition per serving

Calories1069 kcalProtein50.7 gFat68.8 gCarbs59.1 gSugar16.5 gFiber4.3 gSodium1486 mg

Dietary labels

Gluten-free: yesLactose-free: noDairy-free: no

Allergen check

Gluten / wheat: not detectedMilk / dairy: containsEgg: not detectedFish: not detectedShellfish: not detectedPeanut: not detectedTree nuts: not detectedSoy: not detectedSesame: not detectedMustard: containsCelery: not detectedSulphites: not detectedLupin: not detectedMolluscs: not detected

Values are calculated per serving from ingredient amounts and the ingredient nutrition reference per 100g. Allergen and diet labels use available ingredient metadata and name matching; always check product labels for strict diets or allergies. Some ingredient amounts or nutrition values were incomplete, so this is marked as a partial estimate.


Ingredients

Brussels Sprouts8 ounce Brussels SproutsView ingredient guide
Yukon Gold Potatoes12 ounce Yukon Gold PotatoesView ingredient guide
Garlic2 clove GarlicView ingredient guide
Lemon1 unit LemonView ingredient guide
Sour Cream2 tablespoon Sour CreamView ingredient guide
Rosemary0.25 ounce RosemaryView ingredient guide
Beef Demi-Glace1 unit Beef Demi-GlaceView ingredient guide
Dijon Mustard2 teaspoon Dijon MustardView ingredient guide
Chili Flakes1 teaspoon Chili FlakesView ingredient guide
Vegetable Oil2 teaspoon Vegetable OilView ingredient guide
Olive Oil2 teaspoon Olive OilView ingredient guide
Butter2 tablespoon ButterView ingredient guide
SaltSaltView ingredient guide
PepperPepperView ingredient guide

Instructions

  1. Preheat oven to 425°F. Wash and dry all produce. Trim and halve Brussels sprouts lengthwise. Mince or grate 1 clove garlic (2 cloves for 4 servings). Zest and halve lemon. Dice potatoes into ½-inch pieces (no need to peel); place in a large pot with enough salted water to cover. Bring to a boil and cook until tender, 15-20 minutes. Reserve ½ cup potato cooking liquid, then drain.
  2. Melt 1 tablespoon butter (2 tablespoons for 4 servings) in same pot over low heat. Add minced garlic and cook until fragrant, about 30 seconds. Return potatoes to pot; mash with a potato masher until smooth, adding splashes of reserved potato cooking liquid as needed. Stir in sour cream; season with salt and pepper. Keep covered until ready to serve.
  3. Meanwhile, toss Brussels sprouts in a large bowl with a large drizzle of olive oil and a pinch of salt and pepper. Place Brussels sprouts and 1 lemon half (both halves for 4 servings) cut side down on a baking sheet. Roast on top rack until golden brown, 20-25 minutes.
  4. Meanwhile, pat beef dry with paper towels; season generously with salt and pepper. Heat a large drizzle of oil in a large pan over medium-high heat. Add beef and cook to desired doneness, 4-7 minutes per side. Turn off heat; transfer to a cutting board to rest. Wipe out pan.
  5. Melt 1 tablespoon butter (2 tablespoons for 4 servings) in same pan over medium heat. Add remaining garlic and 1 sprig rosemary (2 sprigs for 4); cook, stirring, until fragrant, 30-60 seconds. Reduce heat to low. Add demi-glace, mustard and ¼ cup water (⅓ cup for 4 servings). Cook, stirring, until thoroughly combined, 1-2 minutes. Stir in any resting juices from beef. Turn off heat. Season with salt and pepper. Remove and discard garlic and rosemary.
  6. Slice beef against the grain. Top Brussels sprouts with as much juice from roasted lemon as you like; sprinkle with lemon zest and chili flakes to taste. Divide beef, Brussels sprouts and mashed potatoes between plates. Spoon sauce over beef and serve.

Recipe Tips

For the best sear, make sure the pan is hot before adding the beef and pat the steaks very dry.

Let the beef rest for at least 5 minutes before slicing to keep the juices inside.

If you don’t have a potato masher, use a fork or a hand mixer for the mashed potatoes.

FAQ

Can I use a different cut of beef?

Yes, you can substitute with filet mignon or sirloin steak, but adjust cooking time accordingly.

What can I use instead of demi-glace?

You can use beef broth or stock reduced with a little cornstarch to thicken, but the flavor will be less rich.

How do I store leftovers?

Store components separately in airtight containers in the refrigerator for up to 3 days. Reheat gently.

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