Let Me Tell You About My Favorite Holiday Bite
Alright, pull up a seat because I need to gush for a sec—these steak crostini with horseradish sauce and caramelized onions have become my secret holiday weapon. I still remember the first year I made them; my brother actually asked (with his mouth *full*, by the way) if I’d finally given up store-bought appetizers and joined the ranks of ‘real’ home cooks. As if opening cheese and crackers isn’t culinary magic, too. Anyway, ever since, it’s been the first dish to disappear from the buffet. I once caught my neighbor trying to “save a few for later” in her purse. That’s how you know you’ve hit steak-appetizer gold.
Why You’ll Love These (or At Least End Up Making More Than You Thought)
I make these steak crostini when I want to look like I fussed in the kitchen (but really, it’s mostly tossing a pan and standing around eating onion bits when nobody’s looking). My family goes bonkers for the horseradish sauce—my cousin even requests extra to swipe onto her turkey the next day. Oh, and if you’re anything like me and easily distracted, you’ll love how nothing here needs to be piping hot. I used to burn the toast half the time, now I just make extra and hide any casualties under extra onions (problems solved, right?).
What You’ll Need (And What You Can Totally Swap)
- 1 baguette, sliced on the bias (*when I forget to pick one up, bagels in thin slices actually work surprisingly well—don’t ask unless you’re desperate…)
- 2 tbsp olive oil (or just some butter if it’s what you grabbed first. Mom swears by Irish butter, I never notice)
- 250g (about 9oz) steak, ideally sirloin or ribeye (flank works, but gets chewy… Thin leftover steak from last night also does wonders)
- Salt and pepper, to taste (I go heavy with pepper—personal call)
- 1 large yellow onion, sliced
- 2 tsp brown sugar (technically optional, but I think onions just taste fancier this way)
- 2 tbsp balsamic vinegar (red wine vinegar if you’re out, or skip if you just can’t be bothered)
- Horseradish Sauce:
- 120g (about 1/2 cup) sour cream or Greek yogurt. Full-fat is best but hey, use what you’ve got
- 1-2 tbsp prepared horseradish (add more if you want a sinus-clearing, teary-eyed sort of snack)
- 1 tsp Dijon mustard
- 1 tsp lemon juice
- Pinch salt and black pepper
- Fresh herbs to finish (chives, parsley, whatever’s not threatening to wilt in the fridge)
How To Make This Without Burning Down The Kitchen
- Toast the bread: Lay out those baguette slices on a baking tray, drizzle a bit of oil (or spread a dab of butter if you’re feeling fancy), and bake at 400°F (200°C) until they’re crisp and golden—maybe 8-12 minutes? Flip halfway if you remember. If they look burnt, just scrape it off (been there).
- Caramelize the onions: Get that onion sliced nice and thin. Toss it in a skillet with olive oil over medium-low heat. Add the brown sugar and a pinch of salt. Stir every so often. Let them hang out for at least 20 minutes—don’t rush this, or you’ll have fried onions, which isn’t bad but definitely not as impressive. Hit them with balsamic near the end for that punch. This is where I usually sneak a forkful, for ‘testing’.
- Cook the steak: Salt and pepper the steak generously (don’t be shy). Get a pan screaming hot—another time, I tried with the grill and, actually, pan searing turns out juicier. Two to three minutes per side for medium-rare. Let it rest at least 5 minutes (I always get impatient…but trust me, it ends up juicier if you wait). Then thinly slice across the grain, and maybe snitch a piece for yourself. You’ve earned it.
- The horseradish sauce: Just toss everything in a bowl and stir. Actually, I find it comes together better if you let it sit ten minutes in the fridge, but nobody waits in my house. Use more horseradish for extra zip; sometimes I add a drop of white wine if I’m feeling wild.
- Assemble: Now the fun part. Smear sauce on each crostini, top with a slice or two of steak, then a tangle of those onions. Shower with herbs if you want to impress. Or not—nobody will mind, probably.
A Few Notes I’ve Learned The Hard Way
- Full-fat sour cream in the sauce holds up way better. Tried light once; it just got watery. Not for me.
- Don’t stack the crostini too far ahead—they go a bit soggy if you do it an hour before (found this out at my own New Year’s party, oops…)
- If you run out of fresh steak, leftover roast beef works in a pinch. Nobody seemed to notice except me, and I’m picky.
Some Swaps and Experiments (Not All Were Genius)
- I once swapped in blue cheese crumbles. Not bad, but it overpowers the steak for me—my uncle loved it, though.
- Tried with sweet potato rounds instead of baguette for my gluten-free cousin. They were floppy and cute, but not as crunchy. Maybe slice them thinner next time?
- Did mushrooms instead of steak, too—actually, not half bad if you’re feeding vegetarians, but maybe skip the horseradish. It gets weird.
Tools I Use (But You Can MacGyver It)
- Baking sheet for the bread (but one time I just shoved them under the broiler straight on the rack—it was chaos, but oddly effective. Just keep an eye out for smoke.)
- Decent skillet for onions and steak
- Sharp knife, though in a pinch I’ve used my old bread knife (don’t tell my chef friends)
Storing Leftovers (If You Have Any, Seriously)
Crostini without toppings can live in a sealed bag a couple days, and the steak’s fine covered in the fridge for about 24 hours—but honestly, in my house, it never lasts past breakfast. I do eat the horseradish sauce on eggs the next day, too. But if you do need to store assembled ones, put a paper towel in the container to help avoid full-on sogginess.
How I Serve ‘Em (And How You Might, Too)
I pile these crostini on my largest wooden board, scatter a handful of fresh parsley over top, and serve with a side of pickles—because my family insists pickles must make an appearance at every gathering for some reason. Oh, and don’t forget extra napkins. Kids love these; adults will try to eat them in one bite even though they never fit, which is half the fun.
Things I’ve Learned From Doing This Wrong
- Once, I rushed the onions and ended up with half-raw stringy things. Never again—take your time, it’s worth it.
- I tried slicing the steak right after cooking, and the juice ran everywhere. Let it rest; your bread (and your nerves) will thank you.
Some Questions I Actually Get (And My Honest Answers)
- Can I make the onions ahead? Yes, absolutely! They keep well for a couple days and, actually, I think the flavor gets richer overnight.
- Do I have to use horseradish? Nope. You could try a garlicky aioli or even plain ol’ mayo jazzed up with lemon. Sometimes I use applesauce like on latkes (okay, that’s weird, but I like it!)
- How do you cook steak perfectly? I’m not a steakhouse, but Kenji’s steak guide is fantastic. The key? Hot pan, don’t touch it a million times.
- Do kids eat these? In my experience—yep! But maybe go lighter on the horseradish with the little ones. Or bribe them with extra bread slices (works every time).
- Why is my bread chewy? Probably underbaked or overbaked, or maybe it’s just a rainy day and the air’s weird. Honestly, crostini are kinda forgiving. Serve with wine; nobody cares.
So there you go—my rambly, slightly chaotic guide to Steak Crostini with Horseradish Sauce & Caramelized Onions. If you need more detailed beef tips, this old site rarely lets me down. And if you mess it up? Just tell everyone it’s ‘rustic’. That always works for me.
Ingredients
- 1 baguette, sliced into 1/2-inch rounds
- 2 tablespoons olive oil
- 1 pound sirloin steak
- 2 large yellow onions, thinly sliced
- 2 tablespoons unsalted butter
- 1/2 cup sour cream
- 2 tablespoons prepared horseradish
- 1 tablespoon fresh chives, finely chopped
- Salt and black pepper to taste
Instructions
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1Preheat oven to 400°F (200°C). Arrange baguette slices on a baking sheet, brush with olive oil, and toast for 7-8 minutes until golden.
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2Heat butter in a skillet over medium-low heat. Add sliced onions and cook, stirring occasionally, for 18-20 minutes until deeply caramelized; season with salt and pepper.
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3Season steak with salt and pepper. Heat a grill pan or skillet over high heat. Sear steak for 3-4 minutes per side for medium-rare. Let rest, then slice thinly against the grain.
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4In a small bowl, mix sour cream, prepared horseradish, and chopped chives. Season to taste with salt and pepper to make the horseradish sauce.
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5Top each toasted crostini with a slice of steak, a spoonful of caramelized onions, and a dollop of horseradish sauce. Garnish with additional fresh chives if desired and serve immediately.
Approximate Information for One Serving
Nutrition Disclaimers
Number of total servings shown is approximate. Actual number of servings will depend on your preferred portion sizes.
Nutritional values shown are general guidelines and reflect information for 1 serving using the ingredients listed, not including any optional ingredients. Actual macros may vary slightly depending on specific brands and types of ingredients used.
To determine the weight of one serving, prepare the recipe as instructed. Weigh the finished recipe, then divide the weight of the finished recipe (not including the weight of the container the food is in) by the desired number of servings. Result will be the weight of one serving.
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