Why You’ll Love This Recipe

Portobello French Dip with Horseradish Aioli is a savory, meatless twist on the classic sandwich, loaded with umami-rich portobello mushrooms and served on a crusty roll with a bold horseradish aioli and flavorful au jus for dipping. It’s hearty, satisfying, and perfect for vegetarians or anyone craving a gourmet sandwich experience without the meat.

ingredients

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

portobello mushroomsolive oiloniongarlicsoy saucevegetable broththymebay leafsalt and peppercrusty sandwich rolls (like ciabatta or baguette)

For the Horseradish Aioli:
mayogarlichorseradish (prepared or fresh)lemon juiceDijon mustardsalt and pepper

directions

Clean and slice the portobello mushrooms into thick strips.

In a skillet, heat olive oil over medium heat. Add sliced onions and cook until caramelized.

Add garlic and cook for another minute. Stir in the mushrooms and cook until tender and browned.

Add soy sauce, vegetable broth, thyme, bay leaf, salt, and pepper. Simmer for 10-15 minutes to create a flavorful au jus.

While the mushrooms simmer, prepare the horseradish aioli by mixing mayo, minced garlic, horseradish, lemon juice, Dijon mustard, salt, and pepper until smooth.

Toast the sandwich rolls in the oven or on a skillet until crisp.

Spread horseradish aioli on the bottom half of each roll. Pile on the mushroom and onion mixture.

Serve each sandwich with a small bowl of the strained au jus for dipping.

Servings and timing

This recipe yields 4 sandwiches.Preparation time: 20 minutesCooking time: 20 minutesTotal time: 40 minutes

Variations

Add provolone or Swiss cheese for a melty finish.

Use vegan mayo to make the aioli fully plant-based.

Include sautéed bell peppers for extra color and flavor.

Try balsamic vinegar in the mushroom mix for added depth.

Swap the aioli for garlic butter for a milder option.

storage/reheating

Store the mushroom filling and aioli separately in airtight containers in the fridge for up to 3 days.Reheat the mushrooms gently on the stove before assembling sandwiches.Toast bread fresh for best texture.Do not freeze fully assembled sandwiches, but you can freeze the mushroom mix and au jus for up to 2 months.

FAQs

Can I use another type of mushroom?

Yes, cremini or shiitake also work well, though portobellos offer the meatiest texture.

Is this sandwich spicy?

The horseradish aioli has a mild kick, but you can adjust the heat level to taste.

What bread works best?

Crusty rolls like ciabatta or baguette hold up well to the dipping sauce.

Can I make it vegan?

Yes, just use vegan mayo and check your bread is dairy-free.

Do I need to strain the au jus?

Straining creates a smooth dipping sauce, but it’s optional.

Can I prep this ahead?

Yes, the mushrooms and aioli can be made in advance and reheated for quick assembly.

What goes well on the side?

Serve with fries, a side salad, or roasted vegetables.

Can I add cheese?

Yes, melted provolone or mozzarella complements the flavors beautifully.

Can I grill the sandwich?

Yes, pressing it like a panini gives a crispy crust and melty interior.

Does it taste like traditional French dip?

It offers the same savory satisfaction, with a rich umami flavor from the mushrooms.

Conclusion

Portobello French Dip with Horseradish Aioli is a rich, flavorful sandwich that’s both comforting and refined. With tender mushrooms, creamy aioli, and warm au jus, it’s the perfect vegetarian answer to the beloved French dip. Serve it for lunch, dinner, or anytime you crave something hearty and delicious without the meat.