Sirloin Steak with Mushroom Sauce, Caramelized-Onion Mashed Potatoes, and Roasted Carrots

This sirloin steak recipe is all about rich, meaty flavor elevated by a luscious mushroom pan sauce. Paired with ultra-creamy mashed potatoes studded with sweet caramelized onions and tender roasted carrots, it’s a hearty, satisfying meal that feels special any night of the week.

The secret to the deep, savory sauce lies in the beef demi-glace and earthy button mushrooms, which come together in minutes after searing the steak. With simple techniques and quality ingredients, you can create a restaurant-worthy dinner at home.

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Ingredients

4.5 tablespoon Sour CreamView ingredient guideLike ingredientDislike ingredient

14 ounce Sirloin SteakView ingredient guideLike ingredientDislike ingredient

16 ounce PotatoesView ingredient guideLike ingredientDislike ingredient

1 unit OnionView ingredient guideLike ingredientDislike ingredient

12 ounce CarrotView ingredient guideLike ingredientDislike ingredient

1 unit Beef Demi-GlaceView ingredient guideLike ingredientDislike ingredient

1 clove GarlicView ingredient guideLike ingredientDislike ingredient

2 teaspoon Dijon MustardView ingredient guideLike ingredientDislike ingredient

4 ounce Button MushroomsView ingredient guideLike ingredientDislike ingredient

1 tablespoon (tbsp) ButterView ingredient guideLike ingredientDislike ingredient

1 teaspoon (tsp) SugarView ingredient guideLike ingredientDislike ingredient

teaspoon (tsp) SaltView ingredient guideLike ingredientDislike ingredient

teaspoon (tsp) Black PepperView ingredient guideLike ingredientDislike ingredient

2 tablespoon (tbsp) Cooking OilView ingredient guideLike ingredientDislike ingredient

Instructions

1. Preheat oven to 425°F (220°C). Wash and peel carrots, then cut into 1/2-inch thick sticks. Toss with 1 tablespoon oil, salt, and pepper. Spread on a baking sheet and roast for 20-25 minutes until tender and lightly browned.
2. While carrots roast, peel potatoes and cut into 1-inch cubes. Place in a pot, cover with salted water, and bring to a boil. Cook for 15-20 minutes until fork-tender. Drain and return to pot.
3. Meanwhile, halve and peel onion, then thinly slice. Heat 1 tablespoon oil in a large skillet over medium heat. Add onion and cook, stirring occasionally, until deeply golden and caramelized, about 10-12 minutes. Transfer half the caramelized onion to a small bowl for the sauce; leave the rest in the skillet for the mashed potatoes.
4. Add butter to the skillet with the remaining caramelized onion. Add the cooked potatoes, sour cream, and Dijon mustard. Mash until creamy and smooth. Season with salt and pepper to taste. Cover to keep warm.
5. Pat sirloin steak dry with paper towels and season generously with salt and pepper. In the same skillet (wipe clean if needed), heat 1 tablespoon oil over medium-high heat. Sear steak for 3-4 minutes per side for medium-rare, or until desired doneness. Transfer to a cutting board and let rest for 5 minutes.
6. Reduce heat to medium. Add sliced mushrooms and minced garlic to the skillet. Cook, stirring, until mushrooms are golden and have released their liquid, about 3-4 minutes. Add the reserved caramelized onions, beef demi-glace, and 1/4 cup water. Stir and simmer for 2 minutes until sauce thickens slightly. Season with salt and pepper.
7. Slice the rested steak against the grain. Serve with mashed potatoes, roasted carrots, and spoon the mushroom sauce over the steak.

Recipe Tips

FAQ

Can I use a different cut of steak?

Yes, you can substitute with ribeye, strip steak, or filet mignon. Adjust cooking time accordingly.

Can I make this recipe dairy-free?

Replace butter with a dairy-free alternative and use a dairy-free sour cream. The sauce will still be delicious.

How do I store leftovers?

Store in an airtight container in the refrigerator for up to 3 days. Reheat gently in a skillet or microwave.