Steak crostini are the perfect appetizer for happy hours, cocktail parties, or any holiday gatherings! These easy mini baguette appetizers are topped with grilled, marinated flank steak, horseradish cream, and caramelized onions.
These steak appetizer bites make great holiday crostini because your guests can build their own adventure! Put out all of the different components like horseradish spread and sliced chives and let the guests make their own perfect crostini.
Board or platter-style appetizers are a low-fuss way for party guests to make a plate that they love. To serve alongside this steak crostini appetizer, I'd suggest these Whipped Ricotta Crostini, Whipped Goat Cheese Bruschetta, Grilled Chimichurri Shrimp, or Cheese Tartlets!
Why You'll Love This Recipe
Finger food - Who doesn't love eating bite-sized appetizers at a party? It's perfect to hold a glass in one hand and grab one of the best crostini in the other since you won't need a fork and knife to eat it. Fancy finger food feels so upscale and fun, setting the tone for a great party.
Classy yet simple - Steak screams luxury to me. These steak crostini are deluxe but are surprisingly easy to make. You can make these one-bite appetizers in just a few steps, and you don't even need to assemble them yourself!
Flavor packed - Each component of these little toasts are packed with flavor. The steak gets marinated with soy sauce, brown sugar, and garlic. The onions cook down until they are deeply caramelized. The cream gets a kick from horseradish. And even the baguette toast gets rubbed with garlic!
- Steak. Hanger steak, skirt steak, or flank steak should be used in this recipe. They take well to a marinade and get sliced very thinly, which makes them easy to "ribbon" onto the pieces of toast.
- Onions. Yellow onions should be used, getting sliced very thinly to make the caramelized onions for this dish.
- Horseradish. Prepared horseradish (not horseradish cream or horseradish sauce) will be used. Most times, this is found in one of the refrigerated areas of your grocery store rather than in shelf-stable areas.
- Baguette. I recommend getting a whole baguette and slicing it yourself so you can control the angle and thickness of the slices.
See recipe card for full ingredients list and quantities.
Substitutions and Variations
- Use any cut of steak you'd like. I prefer to use skirt, hanger, or flank for this recipe.
- Omit the caramelized onions if you're not interested in making these.
- Serve with alternative dips, spreads, or cheeses of your choice.
- Use crackers in place of the baguette toasts if you don't want to make toasted bread slices.
Additional Serving Suggestions
There are so many great options of what else you can pair with these steak crostini. I like to think about what flavors go well with steak.
Substitute the horseradish cream with Boursin, blue cheese or burrata. Try topping the crostini with flavorful chimichurri from my Grilled Chimichurri Shrimp recipe. Or top with goat cheese spread and balsamic reduction. These are just a few ideas, but really, the variations are endless!
How to Make This Recipe
This recipe works best when you prep almost everything a day in advance. I suggest marinating the steak, making the caramelized onions, and the horseradish cream on day one.
On day two (when you plan to serve), all you'll have to do is toast the baguette slices and cook the steak.
One: Whisk together all ingredients for the steak marinade.
Two: Add the steak and marinade to a zip-top bag, close tightly, and refrigerate for 4-24 hours.
Three: Peel, half, and very thinly slice the onions.
Four: Add to a large frying pan with olive oil and toss to coat. Cook over low heat.
Five: Stir the onions every 3-5 minutes until golden and jammy. Transfer to a vessel to cool.
Six: Whisk together all ingredients for the horseradish cream. Store in the fridge.
Hot tip! Be patient when caramelizing the onions. This can take up to one hour depending on how thick the onions were sliced.
Seven: Slice the baguette, brush with olive oil, and broil until toasted. Rub with a cut side of a garlic clove.
Eight: Grill or sear the steak in a pan until rare or medium rare. Rest, then slice very thinly against the grain.
Hot tip! Build your board as pictured below and allow guests to make their own crostini, Alternatively, assemble each crostini for an easy grab!
- Marinate the steak and make the caramelized onions and horseradish spread one day in advance, then toast the bread and grill the steak the day you plan to serve the crostini.
- Slice the steak very thin so it can ribbon onto the baguette slices. Slicing this cut of meat too thick will make the bites much too chewy.
- For flank steak, skirt steak, or hangar steak, be sure to slice the meat against the grain or the most tender bites.
- Don't overcook the steak! Cook to medium at the most.
- Allow the steak to come to room temperature before cooking - at least 1 hour on the counter.
Any cut of steak will work, but my favorites are flank, skirt, or hanger steak.
The most accurate way to tell when steak is done cooking is to use a digital meat thermometer to check the temperature. Steak is rare at 120℉, medium rare at 130℉, and medium at 140℉.
I don't suggest cooking this cut of meat past medium because it can become tough. Keep in mind that the temperature will rise 5-10 degrees after removing it from the heat and resting.
If assembling each crostini before serving, don't do it more than 30 minutes before serving or they will get soggy. The steak can be cooked up to one hour in advance and left at room temperature.
Store any leftovers separately in containers in the fridge for up to four days. Place baguette slices in a bag and store at room temperature. Re-toast before serving.
Steak Crostini with Horseradish Cream
- Digital kitchen thermometer
- 1-1½ lbs hanger steak skirt steak, or flank steak
- ⅓ cup soy sauce
- ¼ cup extra virgin olive oil
- 2 tablespoons sugar brown or granulated
- 1 tablespoon apple cider vinegar or balsamic vinegar
- ½ tablespoon dijon mustard
- 1 large garlic clove minced
- 3 large yellow onions
- 2 tablespoons extra virgin olive oil
- ½ cup sour cream
- ½ cup mayonnaise
- 2-4 tablespoons prepared horseradish
- 1 tablespoon apple cider vinegar
- ½ teaspoon kosher salt
- ¼ teaspoon cracked black pepper
- 1 baguette sliced into ½” pieces (about 20-24 slices)
- ¼ cup extra virgin olive oil
- 1 large garlic clove
- fresh chives finely chopped, for garnish
- flaky sea salt for garnish
- Mix together the ingredients for the marinade. Add the steak to a gallon ziptop bag or a dish and pour the marinade overtop. Marinate in the fridge for at least 4 hours, or up to 24 hours.1-1½ lbs hanger steak, ⅓ cup soy sauce, ¼ cup extra virgin olive oil, 2 tablespoons sugar, 1 tablespoon apple cider vinegar or balsamic vinegar, ½ tablespoon dijon mustard, 1 large garlic clove
- Peel, half, and slice the onions very thinly.3 large yellow onions
- Heat a large skillet over medium-low heat. Add the olive oil and onions and toss to coat. Allow the onions to cook for 5 minutes, toss again, then turn the heat to the lowest setting.2 tablespoons extra virgin olive oil
- Continue cooking the onions for 30-40 minutes, stirring every 5 minutes or so, until the onions are golden brown and turn almost jammy-looking. Once cooked, remove from the heat to cool completely.
- Note: If the onions are burning at any point, add ¼ cup of water to loosen any browned bits from the bottom of the pan. The water will evaporate during the remaining cooking process.
- Whisk together all ingredients for the horseradish cream. Taste for seasoning and add more salt as necessary. Cover and store in the fridge for up to 2 days.½ cup sour cream, ½ cup mayonnaise, 2-4 tablespoons prepared horseradish, 1 tablespoon apple cider vinegar, ½ teaspoon kosher salt, ¼ teaspoon cracked black pepper
- Remove the steak from the fridge and let it come to temperature for one hour prior to cooking. Also remove the caramelized onions and horseradish cream so the chill can come off.
- During this time, slice the baguette into ½” slices on the bias, and add to a baking sheet. Brush olive oil onto the tops of all slices, then broil until golden (watch the pieces the whole time).1 baguette, ¼ cup extra virgin olive oil
- Remove from the oven and turn each piece over, then finish broiling until the second side is golden. Cut off the very tip of a peeled garlic clove and rub the cut side of the clove on every piece of toast.1 large garlic clove
- Remove the steak from the marinade and pat dry with paper towels (this will help get a nice, browned crust on the meat).
- Heat a large cast iron skillet or grill on medium high heat until very hot.
- Coat the pan with olive oil, then add the steak. Cook for 2-3 minutes (don’t move it), then flip and cook an additional 2-3 minutes. Continue flipping until your preferred internal temperature is reached (note it will rise another 5-10 degrees during rest time).
- Note: Rare is 120℉, medium rare is 130℉, medium is 140℉. I don’t suggest cooking this cut of meat past medium.
- Rest the steak on a cutting board for 10-15 minutes, then slice the steak into very thin strips (no thicker than ¼”) against the grain, at a 45-degree angle.
- *Add the toasts to a platter, then add caramelized onions, steak, and horseradish cream to each crostini. Finish with chopped fresh chives and flaky sea salt.fresh chives, flaky sea salt