Why You’ll Love This Recipe

Portobello French Dip with Horseradish Aioli is a bold, savory sandwich that offers all the richness of a traditional French dip—without the meat. Meaty portobello mushrooms are sautéed with onions and garlic, then layered onto toasted rolls with melty cheese and a zesty horseradish aioli. Served with a warm, flavorful au jus for dipping, this vegetarian twist is hearty, satisfying, and full of umami.

ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

portobello mushroom capsyellow oniongarlic clovesolive oilsoy sauce or tamarivegetable brothWorcestershire sauce (vegetarian, if needed)provolone or Swiss cheesecrusty sandwich rolls (hoagie or ciabatta)

For the Horseradish Aioli:
mayonaiseprepared horseradishlemon juiceDijon mustardsalt and black pepper

directions

Clean and slice portobello mushrooms into thick strips.

In a large skillet, heat olive oil over medium heat and sauté sliced onion until caramelized, about 10-12 minutes.

Add garlic and mushrooms and cook until mushrooms release moisture and begin to brown.

Stir in soy sauce and Worcestershire sauce and cook for another 2-3 minutes.

Pour in vegetable broth and simmer for 5 minutes to create the dipping au jus. Season with salt and pepper to taste.

In a small bowl, whisk together mayo, horseradish, lemon juice, Dijon, salt, and pepper to make the aioli.

Toast the sandwich rolls until golden.

Spread horseradish aioli on the insides of the rolls.

Layer mushroom mixture and provolone cheese onto the rolls. Broil briefly to melt cheese if desired.

Serve sandwiches hot with a small bowl of warm au jus on the side for dipping.

Servings and timing

This recipe yields 4 sandwiches.Preparation time: 15 minutesCooking time: 20 minutesTotal time: 35 minutes

Variations

Use gruyère, white cheddar, or mozzarella in place of provolone.

Add sautéed bell peppers or spinach for extra veggies.

Make it vegan with plant-based mayo and cheese.

Use French baguette or sourdough instead of hoagie rolls.

Add a splash of red wine or balsamic vinegar to the au jus for depth.

storage/reheating

Store leftover mushroom filling in an airtight container in the fridge for up to 3 days.Store au jus separately and reheat both in a skillet or microwave before assembling sandwiches.Aioli can be made ahead and kept refrigerated for up to 1 week.Assemble just before serving for best texture.

FAQs

Can I use other mushrooms?

Yes, cremini or shiitake also work, but portobellos offer the best “meaty” texture.

Is horseradish aioli spicy?

It has a sharp bite but is mellowed by the mayo—adjust to taste.

Can I skip the cheese?

Yes, or use a dairy-free option for vegan versions.

Do I have to toast the rolls?

Toasting adds texture and helps prevent sogginess—highly recommended.

Can I freeze the mushroom mixture?

It’s best fresh, but you can freeze it in a pinch and reheat in a skillet.

Is Worcestershire sauce vegetarian?

Traditional versions are not, but vegetarian varieties are widely available.

What’s the best bread to use?

Hearty rolls like ciabatta or hoagies hold up well to the filling and dipping.

How do I thin the aioli?

Add a touch of water or lemon juice for a lighter, drizzle-friendly consistency.

Is this filling enough for dinner?

Yes, it’s satisfying and pairs well with soup or a side salad for a full meal.

Can I prep this ahead?

Yes—make the mushroom mixture and aioli ahead, and assemble sandwiches when ready to eat.

Conclusion

Portobello French Dip with Horseradish Aioli is a rich, flavorful sandwich that proves meatless meals can be just as satisfying. With its tender mushroom filling, creamy aioli, and savory au jus, this recipe delivers the classic French dip experience in a fresh, modern, and vegetarian-friendly way.