This is one of those weeknight wins that feels like a treat without a fuss. A nicely broiled sirloin, browned at the edges and finished with a glossy mustard-sour cream sauce, comes together fast and cleans up even faster. It’s an excellent way to get a satisfying, restaurant-style plate on the table on a busy night.

I like this recipe because it focuses on technique—scoring the steak, watching the broiler, and resting the meat—rather than long marinades or complicated steps. The sauce is made in the same pan you used to sauté mushrooms, so it picks up those browned bits and stays flavorful. Serve it with steamed green beans and a simple starch and you’ve got a complete dinner.

Below I’ll walk you through a tidy shopping list, the exact ingredients, the step-by-step broiling method, smart equipment choices, and common mistakes to avoid. Read the quick method and the tips, then get the broiler humming—this one delivers fast, and it delivers well.

Shopping List

10ouncestop sirloin
Freshly ground black pepper
Salt
1cupsliced mushrooms*
1green onionthinly sliced
1clovegarlicdiced
1cupbeef broth
2tablespoonssour cream
1tablespoonDijon mustard
Steamed green beans
Aluminum foil (for lining the baking sheet)

Ingredients

10ouncestop sirloin — the main protein; choose a single piece for even broiling and score for better sear.
Freshly ground black pepper — adds bright spice; grind just before seasoning for best flavor.
Salt — essential for seasoning and bringing out meat flavor; use sparingly if your broth is salty.
1cupsliced mushrooms* — give the sauce an earthy base and soak up pan flavors as they brown.
1green onionthinly sliced — adds a mild onion lift without overpowering; slice thin so it softens quickly.
1clovegarlicdiced — a little garlic for depth; add briefly so it doesn’t burn.
1cupbeef broth — the liquid base for the sauce; reduces to concentrate flavor.
2tablespoonssour cream — lends silkiness and tang to the sauce; stir in off the heat.
1tablespoonDijon mustard — gives the sauce its signature sharpness and body.
Steamed green beans — the suggested vegetable; they provide texture and a fresh contrast to the meat.

Make Broiled Steak With Mustard Sauce: A Simple Method

Preheat the broiler to high. Line a rimmed baking sheet with foil.
Lightly score shallow cuts on both sides of the 10ouncestop sirloin (if the sirloin is in smaller pieces, score each piece).
Sprinkle both sides of the steak generously with freshly ground black pepper and salt.
Place the steak on the prepared baking sheet and broil 4 to 6 minutes per side, until the steak reaches your desired level of doneness.
Remove the steak from the oven, tent loosely with foil, and let rest for at least 5 minutes before slicing.
While the steak cooks, heat a medium skillet over medium heat.
Add the 1 cup sliced mushrooms and the thinly sliced green onion to the skillet. Sauté, stirring occasionally, until the mushrooms are lightly browned, about 3 to 4 minutes. If they begin to stick, add a small splash of the beef broth.
Add the diced clove of garlic and cook, stirring, for about 30 seconds. Transfer the vegetables to a plate and return the pan to the heat.
Pour 1 cup beef broth into the pan and bring to a simmer. Simmer 3 to 4 minutes, until the broth is reduced by about half.
Remove the pan from the heat and whisk in 2 tablespoons sour cream and 1 tablespoon Dijon mustard until smooth. Taste and add salt and freshly ground black pepper as needed (if you used full-sodium beef broth, you may not need additional salt).
Keep the sauce warm over very low heat if not serving immediately—do not boil.
Slice the rested steak across the grain. Serve the sliced steak with steamed green beans and spoon the mustard sauce over the steak and beans.

Why Cooks Rave About It

It’s straightforward and reliably flavorful. Broiling is a high-heat, quick method that caramelizes the outside of the steak while keeping the inside tender. The scoring step helps render any surface fat and encourages even browning. The mustard-sour cream sauce comes together in minutes and delivers a tangy, creamy contrast to the beef—no complicated emulsions or long reductions needed.

Because most of the work is hands-off—broil, rest, a quick sauté and reduction—you can coordinate sides easily. The method highlights good ingredients and simple technique, which is why both home cooks and busy cooks reach for this kind of recipe.

International Equivalents

This preparation sits in the same family as European mustard sauces and pan-sauced steaks. In France, steak with a mustard sauce (often called “steak au moutarde”) is classic—Dijon-based and frequently finished with cream. In other regions you’ll find similar pairings: beef with a tangy, creamy sauce is a common approach because the acid and richness balance the meat.

If you travel through Central Europe you’ll find beef dishes finished with mustard or horseradish-based sauces. The core idea—seared or broiled meat with a quickly made pan sauce using broth and a touch of cream—is globally familiar. Adjust herbs or aromatics to nod toward a specific cuisine.

Equipment at a Glance

Rimmed baking sheet lined with foil — makes broiling and cleanup simple.
Sharp knife — to score the steak and slice across the grain after resting.
Medium skillet — sauté mushrooms and reduce the beef broth in the same pan.
Tongs — for flipping the steak under the broiler safely.
Instant-read thermometer (optional) — for precise doneness.
Small whisk or fork — to blend sour cream and Dijon into a smooth sauce.

Avoid These Mistakes

Skipping the rest: Cutting into the steak too soon squeezes out juices. Let it rest at least 5 minutes.
Overcrowding the pan: Sauté mushrooms in a single layer for browning. Crowding causes steaming instead of browning.
Broiling too close: If the steak is right up against the broiler, it can char before the center cooks. Watch the rack position.
Boiling the sauce: After adding sour cream, do not boil. High heat can split the sauce.
Underseasoning the sauce: Taste after adding sour cream and mustard—broth sodium varies, so adjust carefully.

Make It Diet-Friendly

This dish adapts well without losing what makes it good. Keep the beef but control portions—slice thin and serve with a generous portion of steamed green beans and a modest spoonful of sauce. Because the sauce is concentrated, a little goes a long way.

If you want to cut calories from the sauce, use less sour cream when whisking it in, or skip it entirely and let the reduced beef broth and mustard stand as a lighter pan sauce. Use low-sodium beef broth to control salt, and trim any excess fat from the sirloin before broiling.

Cook’s Notes

Timing and Doneness

Broil 4 to 6 minutes per side as written—this range will put a 10-ounce top sirloin roughly from medium-rare to medium depending on your broiler’s power and the steak’s thickness. Use an instant-read thermometer if you want precision: 125–130°F for medium-rare, 135°F for medium.

Scoring Tip

Light scoring is shallow—just cut the fat or surface a little so the heat can create more surface contact and better browning. Don’t cut deep into the meat.

Sauce Stability

Whisk the sour cream and Dijon in off the heat to avoid curdling. Keep the sauce over very low heat if you hold it briefly, and stir occasionally.

Best Ways to Store

Refrigerate cooked steak: Wrap tightly or place in an airtight container and refrigerate up to 3 days.
Store sauce separately: Keep sauce in a sealed container in the fridge for 2–3 days to preserve texture.
Reheat gently: Warm slices in a skillet over low heat or in the oven at a moderate temperature. Reheat sauce slowly over low heat and whisk to recombine; do not boil.

Final Thoughts

This broiled steak with mustard sauce is a practical, satisfying meal—fast enough for weeknights, deliberate enough to feel like a plan. The method highlights what you already like about steak: good sear, resting for juiciness, and a simple sauce that complements rather than overwhelms. Follow the steps, watch the broiler, and keep the sauce mellow and creamy. You’ll have a reliable go-to that’s elegant enough for guests but simple enough for a Tuesday.

If you try it, slice across the grain, spoon the sauce over the meat and steamed beans, and enjoy how a few focused steps make a memorable plate.

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