Caramelized Onion Sirloin Steak with Rosemary Potatoes and Lemon Asparagus

This elegant steak dinner proves that simple ingredients can create something truly special. The star is the humble onion, slowly caramelized until it’s rich, sweet and deeply savory. Piled high on a perfectly seared sirloin steak, it’s a combination that feels indulgent yet approachable.

Alongside, you’ll find crispy roasted fingerling potatoes perfumed with fresh rosemary and tender asparagus brightened with lemon zest. A tangy horseradish cream sauce adds a final punch of flavor. This is the kind of meal that makes any night feel like a celebration.

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Ingredients

1.5 tablespoon Sour CreamView ingredient guideLike ingredientDislike ingredient

12 ounce Sirloin SteakView ingredient guideLike ingredientDislike ingredient

1 unit OnionView ingredient guideLike ingredientDislike ingredient

6 ounce AsparagusView ingredient guideLike ingredientDislike ingredient

1 unit LemonView ingredient guideLike ingredientDislike ingredient

0.008 ounce RosemaryView ingredient guideLike ingredientDislike ingredient

0.75 teaspoon Dried ThymeView ingredient guideLike ingredientDislike ingredient

1 unit Beef Stock ConcentrateView ingredient guideLike ingredientDislike ingredient

12 ounce Fingerling PotatoesView ingredient guideLike ingredientDislike ingredient

1 ounce Creamy Horseradish SauceView ingredient guideLike ingredientDislike ingredient

2 tablespoon MayonnaiseView ingredient guideLike ingredientDislike ingredient

1 teaspoon Garlic PowderView ingredient guideLike ingredientDislike ingredient

1 teaspoon (tsp) SugarView ingredient guideLike ingredientDislike ingredient

4 teaspoon (tsp) Cooking OilView ingredient guideLike ingredientDislike ingredient

1 tablespoon (tbsp) ButterView ingredient guideLike ingredientDislike ingredient

teaspoon (tsp) SaltView ingredient guideLike ingredientDislike ingredient

teaspoon (tsp) Black PepperView ingredient guideLike ingredientDislike ingredient

Instructions

1. Preheat the oven to 450°F (232°C) with a rack in the middle. Wash and dry all produce. Halve the fingerling potatoes lengthwise. Strip the rosemary leaves from the stems and finely chop until you have 1/4 teaspoon (use 1/2 teaspoon for 4 servings). Halve, peel and thinly slice the onion. Zest the lemon, then quarter it. Trim and discard the woody bottom ends of the asparagus.
2. On one side of a baking sheet, toss the halved potatoes with a drizzle of oil, the chopped rosemary, salt and pepper. Roast on the middle rack for 14 minutes. (For 4 servings, spread the potatoes across the entire sheet.)
3. Meanwhile, heat a drizzle of oil in a medium nonstick pan (use a large pan for 4 servings) over medium-high heat. Add the sliced onion and 1/4 teaspoon dried thyme (1/2 teaspoon for 4 servings). Cook, stirring occasionally, until the onion is browned and softened, 5-8 minutes. Stir in the beef stock concentrate, 1/4 cup water, 1 teaspoon sugar and 1 teaspoon lemon juice (for 4 servings: 1/2 cup water, 2 teaspoons sugar, 2 teaspoons lemon juice). Cook until thickened and saucy, 2-3 minutes more. Remove from heat and stir in 1 tablespoon butter (2 tablespoons for 4 servings) until melted. Taste and season with salt and pepper if desired. Transfer the onion mixture to a medium microwave-safe bowl and cover tightly with plastic wrap. Rinse and wipe out the pan.
4. In a second medium bowl, combine the sour cream, horseradish sauce, mayonnaise and a squeeze of lemon juice. Season with salt and pepper to taste. Pat the steak dry with paper towels and season generously on all sides with garlic powder, 1/2 teaspoon dried thyme (1 teaspoon for 4 servings), salt and pepper.
5. After the potatoes have roasted for 14 minutes, remove the baking sheet from the oven. Carefully toss the asparagus on the opposite side of the sheet with a drizzle of oil, salt and pepper. Return the sheet to the middle rack and roast until the vegetables are lightly browned and tender, 10-12 minutes more. (For 4 servings, leave the potatoes roasting; place the asparagus on a second baking sheet and roast on the top rack.)
6. Heat a large drizzle of oil in the same pan used for the onion over medium-high heat. Add the steak and cook until browned and cooked to your desired doneness, 3-6 minutes per side. Turn off the heat and transfer the steak to a cutting board to rest for 5 minutes.
7. If needed, reheat the saucy onion in the microwave for 15-20 seconds. Toss the roasted asparagus with as much lemon zest as you like. Slice the rested steak against the grain. Divide the steak, asparagus and potatoes among plates. Top the potatoes with the saucy onion and drizzle the steak with the horseradish cream. Serve with the remaining lemon wedges on the side.

Recipe Tips

FAQ

Can I use a different cut of steak?

Yes, you can substitute sirloin with ribeye, strip steak or filet mignon. Adjust cooking time based on thickness and desired doneness.

What can I use instead of horseradish cream?

If you don’t have horseradish cream, mix prepared horseradish with sour cream or mayonnaise to taste. You can also omit it for a milder sauce.

Can I prepare the caramelized onions ahead of time?

Absolutely! Cook the onions as directed, then store them in an airtight container in the refrigerator for up to 3 days. Reheat gently before serving.