Crostini Steak Toppers
Crostini Steak Toppers are toasted baguette slices topped with seared steak, a swipe of horseradish cream, and a warm mushroom-onion topper. It’s the kind of appetizer I’d rather put out than a fussy cheese board because it actually eats like a bite of dinner.
The flavors are bold but familiar: beefy and savory, a little tangy from horseradish, and that deep, almost sweet browned mushroom thing going on. I like this version because it feels balanced—creamy, crisp, and meaty—without needing a bunch of extra garnishes.
These are especially good for holiday platters, casual get-togethers, or when I want something that looks a little special but still feels straightforward. They also pair really well with a simple salad or a glass of red wine, and I like that you can prep parts ahead and just cook the steak right before serving.
Why You’ll Love This Recipe
Real dinner flavor: Steak, mushrooms, and horseradish is a classic combo for a reason. It tastes like a full meal, just in a small bite.
Crisp + creamy: The crostini stays crunchy while the horseradish cream adds that cool, tangy layer that keeps it from feeling heavy.
Easy to scale: You can make a small tray for a weeknight snack situation or double it for a party without changing anything.
Make-ahead friendly: The sauce and crostini can be done earlier, so you’re not juggling everything at once right before guests show up.
Flexible toppings: Blue cheese, parmesan, extra herbs, a little cayenne—this one is easy to tweak based on who you’re feeding.
Key Ingredients
Crostini
- Baguette: I like a standard French baguette here because it slices cleanly and toasts up crisp. Try to cut the slices evenly so they brown at the same pace.
- Olive oil: This helps the crostini toast instead of drying out. Use whatever you normally cook with.
- Garlic: Rubbing the warm toast with a cut clove gives you garlic flavor without making the whole bite taste “garlicky.”
- Kosher salt: Don’t skip it—salt on the bread makes the whole appetizer taste more finished.
Steak
- Sirloin steak: Sirloin is my go-to because it’s affordable and still tender when you slice it thin across the grain. Ribeye or tenderloin work too if you want to splurge.
- Olive oil: A light coating helps the seasoning stick and keeps the steak from grabbing the pan.
- Kosher salt: Seasoning the steak well matters since each crostini only gets a couple slices.
- Black pepper: Freshly ground is best, but use what you have.
- Smoked paprika (optional): I like it for a little smoky warmth, especially if you’re not adding any extra heat later.
Mushroom Onion Topper
- Butter: Butter gives the mushrooms that savory base that olive oil just doesn’t quite match.
- Cremini mushrooms: They brown nicely and have more flavor than white mushrooms. Slice them so they cook evenly and don’t steam.
- Red onion: Finely diced is the move here so it softens quickly and doesn’t overpower the bite.
- Garlic: Fresh is best here. Adding it near the end keeps it from getting bitter.
- Balsamic vinegar: This adds a little sweetness and tang once the mushrooms are browned.
- Worcestershire sauce: A small amount gives the topper that savory, steakhouse-style depth.
- Salt: Season to taste at the end since the Worcestershire brings salt too.
- Black pepper: A few turns at the end is usually enough.
- Fresh parsley: This brightens everything up and makes the topping look less brown-on-brown.
Horseradish Cream
- Sour cream: This gives you that cool, creamy base. Greek yogurt works if you want it a little tangier and thicker.
- Prepared horseradish: Use the jarred kind and drain it so the sauce doesn’t get watery.
- Mayonnaise: Just a bit makes the sauce smoother and a little richer.
- Dijon mustard: Dijon plays nicely with horseradish and keeps the flavor sharp.
- Lemon juice: A small squeeze helps wake the whole sauce up.
- Salt: Add a pinch, then taste. Horseradish brands vary a lot.
Recipe Instructions
- Preheat the oven: Heat the oven to 400°F and set a baking sheet on the counter.
- Toast the bread: Arrange the baguette slices on the baking sheet, brush both sides with olive oil, and sprinkle with kosher salt. Bake until crisp and lightly golden.
- Rub with garlic: While the crostini are still warm, rub the cut side of the garlic clove over the tops. Let the crostini cool slightly so they stay crisp.
- Season the steak: Pat the steak dry, then coat with olive oil, salt, pepper, and smoked paprika if you’re using it.
- Sear the steak: Heat a skillet over high heat, then sear the steak for about 3 to 5 minutes per side, depending on thickness and how done you want it.
- Rest and slice: Rest the steak for 5 minutes, then slice thinly against the grain.
- Cook the mushrooms and onion: In the same skillet, melt the butter, then sauté the mushrooms and red onion until browned and the moisture has cooked off.
- Add garlic and finish: Stir in the minced garlic for about 30 seconds, then stir in the balsamic vinegar and Worcestershire sauce. Season with salt and pepper, remove from heat, and stir in the parsley.
- Mix the horseradish cream: Stir the sour cream, horseradish, mayonnaise, Dijon, lemon juice, and salt until smooth.
- Assemble: Spread a thin layer of horseradish cream on each crostini, top with steak slices, then spoon on the mushroom-onion topper. Serve right away.
My Tips!
This is the section that separates “good” from “wow.” If you read only one part of this post, make it this one — it’s where I reveal my recipe trick.
Recipe Tips & Tricks
Slice the steak against the grain. This is the difference between tender bites and chewy ones, especially with sirloin. I aim for thin slices so each crostini is easy to eat.
Let the mushrooms really brown. If the pan is crowded or the heat is too low, they’ll steam and turn soft. Give them space and keep cooking until the moisture is gone.
Drain the horseradish. Prepared horseradish can carry a lot of liquid, and that can thin out the sauce fast. A quick drain keeps the cream thick and spreadable.
Keep the crostini crisp. Don’t assemble too early or the bread will soften from the sauce and topping. I like to set everything out and build right before serving.
Season as you go. The topping and steak both need salt, but Worcestershire and Dijon add salt too. Taste the mushroom mixture at the end and adjust.
Simple tweaks
Here’s where the fun begins — a few simple tweaks can turn this recipe from casual treats into the star of any party.
Serving Suggestions
- Salad: A simple arugula salad with lemon and olive oil is great with these. Something light is nice next to the rich steak and sauce.
- Veggie side: I like a tray of roasted asparagus or green beans, especially if I’m serving this as part of a bigger spread.
- Extra sauce: Put a small bowl of horseradish cream on the platter for people who want more. It’s also good with any leftover steak.
- Drinks: Red wine is the obvious choice, but a cold beer works too. Anything not too sweet is good here.
Eat it later
This section explains how to store leftovers properly and how far in advance the recipe can be prepared.
Storage and Make Ahead
Store leftovers covered in the fridge for up to 3 days. I keep the crostini, steak, topper, and sauce separate if I can. Assembled crostini will soften pretty quickly.
You can make the horseradish cream ahead and keep it chilled until you’re ready to serve. It may thicken a little in the fridge, which is totally fine for spreading.
Toast the crostini earlier in the day and leave them at room temperature once fully cooled. If they soften, pop them back in a 400°F oven for a couple minutes to crisp them again.
For the steak and mushroom topper, I prefer cooking them close to serving time, but you can rewarm leftovers gently in a skillet. Keep the heat low so the steak doesn’t overcook.
It could help!
Before you close the tab or print the recipe, scroll through these quick answers.
Recipe FAQs
What cut of steak works best for crostini?
Sirloin is a great everyday option because it has good flavor and stays tender if you slice it thin. Ribeye is richer, and tenderloin is the most tender, but either one will cost more.
Can I make these without horseradish?
You can, but you’ll want something tangy to replace it. I’d mix sour cream with a little Dijon and lemon juice, or even use a simple garlic aioli.
How do I keep the crostini from getting soggy?
Assemble right before serving. If you need to set up a platter, keep the sauce and toppings on the side and let people build their own.
Can I cook the steak to medium-well?
Yes. Just know that sirloin gets a little chewier the more it cooks, so slicing thin becomes even more important. Resting the steak before slicing helps too.
What else can I add on top?
Crumbled blue cheese is really good if you like that steakhouse flavor. Shaved parmesan is a milder option, and a pinch of cayenne in the sauce adds some heat.
Keep it with you
The printable version with print button is at the end of the post, easy to follow, and includes all the steps you’ll need.
MORE RECIPES TO TRY
Crostini Steak Toppers
Ingredients
Crostini
- 1 baguette sliced into 24 pieces
- 2 tbsp olive oil
- 1 clove garlic halved
- ½ tsp kosher salt.
Steak
- 1 lb sirloin steak
- 1 tbsp olive oil
- 1 tsp kosher salt
- ½ tsp black pepper
- ½ tsp smoked paprika optional.
Mushroom Onion Topper
- 1 tbsp butter
- 8 oz cremini mushrooms sliced
- ½ cup red onion finely diced
- 2 cloves garlic minced
- 2 tsp balsamic vinegar
- 1 tsp Worcestershire sauce
- salt to taste
- black pepper to taste
- 2 tbsp fresh parsley chopped.
Horseradish Cream
- ½ cup sour cream
- 2 tbsp prepared horseradish drained
- 1 tbsp mayonnaise
- 1 tsp Dijon mustard
- 1 tsp lemon juice
- salt to taste.
Instructions
Crostini
- Heat oven to 400 F and place baguette slices on a baking sheet
- brush both sides with 2 tbsp olive oil and season with 0.5 tsp salt
- bake until crisp and lightly golden then rub warm crostini with cut garlic and cool slightly.
Steak and Topper
- Pat steak dry then coat with 1 tbsp olive oil
- 1 tsp salt
- 0.5 tsp pepper and paprika if using
- sear in a hot skillet 3 to 5 minutes per side to desired doneness then rest 5 minutes and slice thinly against the grain
- in the same skillet melt butter then saute mushrooms and onion until browned and moisture evaporates then stir in garlic for 30 seconds and finish with balsamic and Worcestershire plus salt and pepper then remove from heat and stir in parsley.
Horseradish Cream and Assemble
- Stir sour cream
- horseradish
- mayonnaise
- Dijon
- lemon juice and salt until smooth
- spread a thin layer of horseradish cream on each crostini then top with steak slices and a spoon of mushroom onion topper and serve immediately.
