If you’re craving a sandwich that’s bursting with bold flavors and a perfect balance of fresh herbs, tangy mustard, and savory steak, these dwiches with Gremolata and Mustard Sauce are exactly what you need. Juicy, balsamic-marinated sirloin meets vibrant gremolata and a creamy, zesty mustard sauce, all nestled inside a crusty baguette with peppery arugula and ripe heirloom tomatoes. Every bite delivers layers of texture and flavor that will have you coming back for more, whether it’s a quick lunch or a show-stopping dinner.

dwiches with Gremolata and Mustard Sauce Recipe - Recipe Image

Ingredients You’ll Need

These ingredients are deceptively simple but critical; each one plays an important role in creating the rich, fresh, and tangy flavor profile that makes these dwiches with Gremolata and Mustard Sauce unforgettable. From the tender marinated steak to the zesty gremolata and creamy mustard sauce, every component adds something special.

Sirloin steak, 1 lb: Choose a well-marbled cut for juicy, tender slices that soak up the marinade beautifully.
Balsamic vinegar, 2 tablespoons: Adds deep, slightly sweet acidity to balance the savory steak.
Worcestershire sauce, 1 tablespoon: Enhances umami with subtle smoky and tangy notes.
Extra virgin olive oil, 1/4 cup + drizzle: Rich and fruity, it tenderizes the steak and gives the bread a golden toast.
Dijon mustard, 1/2 teaspoon + 2 teaspoons: Brings a sharp bite for both marinade and mustard sauce layers.
Garlic powder, 1/4 teaspoon: Simple seasoning that boosts the steak’s flavor.
Coarse salt and ground black pepper: Essential for seasoning and drawing out the steak’s natural flavors.
Whole grain mustard, 1 teaspoon: Adds texture and a rustic tang to the mustard sauce.
Mayonnaise, 1 teaspoon: Creates creaminess and mellows the mustard’s heat.
Horseradish, 1/4 teaspoon: Delivers a subtle kick that wakes up your taste buds.
Basil leaves, 2 tablespoons minced: Gives the gremolata its bright, sweet herbal note.
Parsley, 2 tablespoons minced: The fresh backbone of the gremolata, bringing vibrancy and a hint of earthiness.
Garlic clove, 1 minced: Adds pungent depth to the gremolata mix.
Lemon zest, 1 tablespoon: Infuses the gremolata with uplifting citrus brightness.
French baguette, cut in half and sliced lengthwise: A crusty, airy base to hold all the delicious fillings.
Baby arugula, 1 1/2 to 2 cups: Peppery greens that add a fresh crunch and balance richness.
Heirloom tomato, sliced: Juicy and sweet, providing a refreshing contrast to the savory steak.
Blue cheese, 1/4 to 1/2 cup crumbled: Optional but highly recommended for sharp, creamy bursts of flavor.

How to Make Sandwiches with Gremolata and Mustard Sauce

Step 1: Marinate the Steak

Start by whisking together balsamic vinegar, Worcestershire sauce, olive oil, dijon mustard, garlic powder, salt, and pepper. Place your sirloin steak in a large ziplock bag, pour in the marinade, seal tightly, and shake to coat every inch. Let it chill in the fridge for 30 minutes. This quick marinade step infuses the steak with a beautiful depth of flavor, ensuring each bite is juicy and flavorful.

Step 2: Prepare the Gremolata

While the steak marinates, mix the minced basil, parsley, lemon zest, and garlic in a small bowl. This fresh herb mixture—called gremolata—adds a zesty, aromatic layer of flavor that lifts the entire sandwich. Set it aside; it’s your secret weapon for an incredible herbaceous pop.

Step 3: Make the Mustard Sauce

In another small bowl, combine dijon mustard, whole grain mustard, mayonnaise, and horseradish. Stir everything together until smooth and creamy. This luscious mustard sauce delivers a tangy, creamy kick that perfectly complements the smoky steak and fresh vegetables.

Step 4: Grill the Steak

Preheat your grill or grill pan to medium-high heat. Remove the steak from the marinade and place it on the hot grill. Cook for about 4-5 minutes per side if you prefer rare to medium-rare doneness. Once cooked, transfer the steak to a plate and allow it to rest for five minutes before slicing thinly against the grain for maximum tenderness.

Step 5: Toast the Baguette

Drizzle olive oil inside your baguette halves and place them on the grill with the crust side up. Toast for 2-3 minutes until you see gorgeous grill marks and the bread gets slightly crispy but still airy inside. Toasting adds crunch and makes sure your sandwich holds up against all those juicy ingredients.

Step 6: Assemble the Sandwiches with Gremolata and Mustard Sauce

Spread the mustard sauce generously on both halves of the toasted bread. On the bottom half, sprinkle half of your blue cheese (if using), then layer with tomato slices, baby arugula, and thin steak slices. Sprinkle the gremolata over the steak, add the remaining blue cheese, and finish with any extra mustard sauce. Top with the other half of the baguette and serve immediately for the ultimate flavor experience.

How to Serve Sandwiches with Gremolata and Mustard Sauce

Garnishes

A handful of additional fresh gremolata sprinkled on top of the sandwich right before serving brightens flavors and adds a gorgeous burst of green that makes these dwiches look as good as they taste. You can also add a drizzle of olive oil or a light sprinkle of coarse sea salt to enhance every bite.

Side Dishes

These dwiches with Gremolata and Mustard Sauce pair beautifully with simple, crunchy sides like kettle-cooked chips, a crisp garden salad, or roasted sweet potato fries. The fresh, herbaceous notes in the sandwich balance perfectly with lighter sides that don’t overpower the steak’s richness.

Creative Ways to Present

For a fun twist, slice the assembled sandwich into smaller sliders for a party platter or serve it open-faced topped with a poached egg for brunch. You can also swap the baguette for ciabatta or focaccia to adjust the texture, making each variation uniquely delicious while still celebrating the core flavors of gremolata and mustard sauce.

Make Ahead and Storage

Storing Leftovers

If you end up with any leftover steak or condiments, store them separately in airtight containers. Keep sliced steak refrigerated for up to 3 days. Store the mustard sauce and gremolata apart from the bread to avoid sogginess. Assemble fresh before serving for the best taste and texture.

Freezing

While the steak can be frozen after cooking, it’s best to freeze it before slicing. Wrap tightly in plastic wrap and foil, then freeze for up to 2 months. Avoid freezing the bread, mustard sauce, or gremolata, as their textures and flavors change upon thawing.

Reheating

Gently reheat steak slices in a skillet over low heat or in the microwave with a damp paper towel to retain moisture. Toast bread again separately before assembling for fresh crunch. Avoid reheating the mustard sauce or gremolata; add fresh before serving.

FAQs

Can I use a different cut of steak for these sandwiches?

Absolutely! Flank or skirt steak works well too. Just be sure to slice thinly against the grain for tenderness. Adjust grilling time based on thickness and preferred doneness.

Is there a vegetarian alternative to steak for this recipe?

For a vegetarian version, try grilled portobello mushrooms marinated similarly, or use thick slices of grilled eggplant or seitan. The gremolata and mustard sauce will still deliver that vibrant flavor punch.

Can I make the mustard sauce and gremolata ahead of time?

Yes! Both can be made up to one day in advance and stored separately in the fridge. Bring to room temperature before assembling the sandwich for best flavor.

How spicy is the mustard sauce?

The horseradish and dijon mustard provide a gentle heat that complements but doesn’t overpower. If you prefer less spice, reduce the horseradish or choose milder mustards.

What can I substitute for blue cheese if I don’t like it?

Try crumbled feta, goat cheese, or omit the cheese altogether. The sandwich is delicious without it, but the blue cheese adds a tangy depth that pairs so well with the gremolata and steak.

Final Thoughts

If you’re looking to elevate your sandwich game to something truly memorable, trying these dwiches with Gremolata and Mustard Sauce is an absolute must. The harmony of fresh herbs, bold mustard, and perfectly grilled steak will make this your new favorite go-to. Go ahead, grab a baguette, fire up the grill, and make someone’s day with this incredible, flavor-packed creation.

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Sandwiches with Gremolata and Mustard Sauce Recipe

★★★★★

5.1 from 19 reviews

Author: Ethan
Total Time: 45 minutes
Yield: 2 large sandwiches 1x
Diet: Low Lactose

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Description

These Grilled Balsamic Steak Sandwiches with Gremolata and Mustard Sauce combine tender, marinated sirloin steak with fresh herbs, tangy mustard sauce, and melty blue cheese, all layered on a toasted French baguette. Perfect for a hearty lunch or casual dinner, this recipe brings together bold flavors and satisfying textures in every bite.

Instructions

Marinate the steak: In a medium bowl, whisk together balsamic vinegar, Worcestershire sauce, olive oil, Dijon mustard, garlic powder, salt, and black pepper. Place the sirloin steak in a large ziplock bag, pour the marinade over it, seal the bag, and shake to coat evenly. Refrigerate for 30 minutes to allow the flavors to infuse.
Prepare the gremolata: In a small bowl, combine the minced basil, parsley, lemon zest, and garlic. Stir and set aside to let the flavors meld.
Make the mustard sauce: Mix together the Dijon mustard, whole grain mustard, mayonnaise, and horseradish in a small bowl until smooth. Set this sauce aside for spreading on the sandwich.
Heat the grill: Preheat an outdoor grill to medium-high heat or use a grill pan over medium-high stove heat.
Grill the steak: Remove the marinated steak from the fridge and place it on the grill. Cook for 4-5 minutes per side for rare to medium-rare doneness. Once cooked, transfer the steak to a plate and let it rest for five minutes to retain juices. After resting, slice thinly against the grain for tenderness.
Toast the baguette: Drizzle olive oil on the cut sides of the baguette halves. Place them on the grill with the crust side up and toast for 2-3 minutes until lightly charred and crisp.
Assemble the sandwiches: Spread the prepared mustard sauce on both the top and bottom halves of the toasted baguette. On the bottom half, sprinkle half of the blue cheese, followed by a layer of sliced heirloom tomato, baby arugula, and the thinly sliced steak. Top with the gremolata, remaining blue cheese, and any leftover mustard sauce. Close the sandwich with the top half of the baguette and serve immediately.

Notes

Marinate the steak for up to 2 hours if you want more intense flavor.
If you prefer a different cheese, try crumbled feta or goat cheese as a tasty alternative to blue cheese.
Adjust the amount of arugula and blue cheese according to your preference for pepperiness and creaminess.
For easier slicing, let the steak rest fully before cutting against the grain to keep it tender.
Use a serrated bread knife to slice the baguette cleanly without crushing it.
Serve with chips, a side salad, or roasted vegetables for a complete meal.

Prep Time: 15 minutes
Cook Time: 15 minutes
Category: Sandwiches
Method: Grilling
Cuisine: American