If you’re craving a flavor-packed, restaurant-quality steak dinner, this Seared London Broil with Garlic Mashed Potatoes and Mushroom Sauce delivers. It’s an easy yet elegant recipe that combines a beautifully marinated and seared London broil steak, creamy garlic mashed potatoes, and a rich, savory mushroom sauce created from the reduced marinade for exceptional depth of flavor. Whether you’re planning a weeknight meal or a special steak night, this dish guarantees tender, juicy steak with bold umami flavors.
What Makes This London Broil Recipe Special?
- Marinated for Maximum Flavor – The soy sauce, balsamic vinegar, Worcestershire, garlic, and herbs create a robust marinade that both tenderizes the steak and infuses it with deep, rich notes.
- Perfectly Seared Steak – Cooking the London broil in a cast-iron skillet creates a beautiful caramelized crust while keeping the inside tender and juicy.
- Garlic Mashed Potatoes – These ultra-creamy mashed potatoes use steamed Yukon gold potatoes for smoother texture. The garlic paste blends seamlessly, infusing the potatoes with deep, roasted garlic flavor.
- Mushroom Sauce with Reduced Marinade – Instead of discarding the marinade, it’s simmered and reduced with mushrooms, shallots, and thyme, creating a luxurious sauce that elevates the steak.
How to Make the Best Seared London Broil
- Marinate thoroughly – Soak the lean meat overnight in an acidic marinade to break down tough fibers
- Prepare for cooking – Bring to room temperature and pat completely dry with paper towels
- Sear properly – Cook in a smoking-hot cast iron skillet for 4-5 minutes per side for medium-rare
- Rest adequately – Let the meat rest for 10 minutes to redistribute juices
- Slice correctly – Cut thinly at an angle against the grain for maximum tenderness
The Secret to Creamy Garlic Mashed Potatoes
Steaming potatoes instead of boiling them retains more flavor and nutrients while preventing excess water absorption. Yukon gold potatoes offer natural creaminess, and mashing them with butter, heavy cream, and garlic paste creates an irresistibly silky-smooth consistency.
Pro Tip: Make your garlic more flavorful and less harsh by mincing it finely and mashing it into a paste with a little salt before adding it to the potatoes. This technique brings out garlic’s natural sweetness and helps it blend seamlessly into the dish.
A Steakhouse-Worthy Mushroom Sauce
The mushroom sauce in this recipe elevates the dish with a deep, earthy umami flavor. Instead of using just broth and cream, the reserved London broil marinade is reduced, intensifying the flavors. Cooking it with cremini or shiitake mushrooms, shallots, and fresh thyme creates the perfect steak sauce that’s bold yet balanced. The mushrooms absorb all the concentrated flavors while adding their own meaty texture. A final touch of butter, swirled in off the heat, adds silky richness and a beautiful sheen to the sauce. Spoon it generously over both the sliced London broil and garlic mashed potatoes for the complete steakhouse experience.
Why You’ll Love This Recipe
- Easy yet gourmet – Tastes like a steakhouse meal but made right in your kitchen.
- Marinated for bold flavor – Guarantees juicy, tender steak every time!
- Perfect for special occasions or meal prep – Flavors deepen overnight for amazing leftovers.
If you love steakhouse-style dinners, this Seared London Broil with Garlic Mashed Potatoes & Mushroom Sauce will become your go-to favorite. The beauty of this recipe lies in its versatility—perfect for a special weekend meal but simple enough for a weeknight dinner that feels extra special. Don’t forget to save some for the next day; the flavors intensify overnight, making leftovers even more delicious. Serve with a bold red wine and a simple green salad for a complete meal that rivals any restaurant experience. Save this recipe, share it with friends, and let’s get cooking!
Seared London Broil with Mushroom Sauce and Garlic Mashed Potatoes
4
servings24
hours30
minutes24
hours30
minutesThis Seared London Broil with Garlic Mashed Potatoes and Mushroom Sauce is a steakhouse-quality meal made at home. A flavorful marinade, creamy garlic mashed potatoes, and a rich mushroom sauce made from the reduced marinade create the perfect balance of umami, tenderness, and indulgence.
Ingredients
- For the London Broil
1 London broil steak (~2 lbs)
1/2 cup soy sauce
1/3 cup extra virgin olive oil
3 cloves garlic, minced
1/4 cup balsamic vinegar
1 cup beef broth
1 tablespoon Worcestershire sauce
1 tablespoon lemon juice
1 tablespoon dijon mustard
2 tablespoons honey
1 teaspoon thyme
1 teaspoon oregano
1 teaspoon ground black pepper
1/2 teaspoon red pepper flakes
- For the Mushroom Sauce
2 cups mushrooms (cremini or shiitake), sliced
1 tablespoon extra virgin olive oil
2 cloves garlic, minced
1 small shallot, minced
1 tablespoon thyme leaves, fresh
1/4 cup heavy cream
1 tablespoon butter
to tase, salt and ground black pepper
2 tablespoons avocado oil
- For the Garlic Mashed Potatoes
1 pound Yukon gold potatoes
1/4 cup heavy cream
2 tablespoons butter
6 cloves of garlic, minced
to taste, salt and ground black pepper
Directions
- Marinate the London Broil:
Whisk together soy sauce, extra virgin olive oil, balsamic vinegar, beef broth, Worcestershire sauce, lemon juice, Dijon mustard, honey, thyme, oregano, black pepper, and red pepper flakes.
Place the London broil in a resealable bag or shallow dish, and pour the marinade over it. Seal and marinate in the refrigerator for at least 4 hours, but preferably overnight. - Prepare the Garlic Mashed Potatoes:
Peel and chop the Yukon gold potatoes into evenly sized chunks. Place the potatoes in a steamer basket over simmering water and steam until fork-tender, about 20-25 minutes.
While the potatoes cook, melt the butter in a small saucepan over low heat. Add the minced garlic and cook until fragrant but not browned, about 1 minute. Drain the potatoes and return them to the pot. Add the garlic butter mixture and heavy cream. Mash until smooth and creamy, seasoning with salt and pepper to taste. Keep warm until ready to serve. - Cook the Mushroom Sauce:
Remove the steak from the marinade and reserve the liquid for the sauce.
Heat the extra virgin olive oil over medium heat in a saucepan. Add the shallots and garlic, and cook until fragrant, 1-2 minutes. Stir in the sliced mushrooms and thyme. Cook until mushrooms soften and begin to caramelize, 5-7 minutes. Pour in the reserved marinade and simmer until reduced by half, about 5-7 minutes. Stir in the heavy cream and butter, and cook for another 2 minutes until slightly thickened. Season with salt and ground black pepper to taste. Keep warm until ready to serve. - Sear the London Broil:
Remove the steak from the fridge 30 minutes before cooking to let it come to room temperature. Heat a cast iron skillet or grill pan over high heat. Oil the pan with avocado oil.
Pat the steak dry and sear for 4-5 minutes per side for medium-rare, or until desired doneness (130-135°F internal for medium-rare). Transfer to a cutting board and let rest for 10 minutes before slicing against the grain. - Serve:
Plate the garlic mashed potatoes, then layer with slices of London broil. Spoon the mushroom sauce over the steak. Garnish with fresh thyme, cracked black pepper, or red pepper flakes, if desired.
Notes
- Garlic paste: To make the garlic more flavorful and less harsh, mince it finely and mash it into a paste with a little salt before adding it to the potatoes. This brings out its natural sweetness and blends seamlessly into the dish.
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