Vegetarian French Dip Recipe

Prepare and roast mushrooms

Preheat oven to 425°F (220°C). Clean portabella caps, remove stems, and gently scrape gills if desired. Brush both sides with 2 tbs olive oil and season with 1 tsp kosher salt, 1 tsp black pepper, and 1 tsp smoked paprika. Place mushroom caps gill-side down on a rimmed baking sheet lined with foil. Roast for 15–18 minutes until tender and juices are released. Flip and roast 3–5 more minutes. Remove and let rest 5 minutes, then slice into 1/4" thick strips.

Prepare bread and cheese

Slice the batard into sandwich-length pieces (makes 4 sandwiches) and then halve lengthwise. Spread softened butter or brush with remaining 1 tbs olive oil on cut sides. Heat a skillet or griddle over medium-high heat and toast the cut sides until golden and crisp, about 2–3 minutes per side. Remove and keep warm. Lay out Swiss cheese slices so they are ready to melt on the roasted mushrooms when assembling.

Assemble sandwiches

On the bottom half of each toasted batard, spoon 1/4 of the eggplant caponata, arrange 3–4 slices of roasted portabella per sandwich, then top mushrooms with 2 slices of Swiss cheese. Place the sandwich under a broiler or in a 375°F (190°C) oven for 2–4 minutes until cheese melts. Remove, top with about 1/2 cup of baby arugula per sandwich (divide 2 cups across 4 sandwiches), close with top half of bread and press lightly. Serve immediately with warm vegetarian au jus for dipping.

Salt the diced eggplant in a colander and let sit 15 minutes to draw out bitterness. Rinse and pat dry thoroughly.

Heat 2 tbs olive oil in a large skillet over medium-high heat. Add diced eggplant and cook, stirring occasionally, until golden and tender, about 8–10 minutes. Transfer eggplant to a plate.

Add remaining 1 tbs olive oil to the skillet. Sauté diced red bell pepper, sliced red onion, and diced celery until softened, about 6 minutes. Add minced garlic and cook 30–60 seconds until fragrant.

Return eggplant to the pan. Stir in tomato paste, red wine vinegar, sugar, capers, chopped olives, salt, and black pepper. Cook 3–5 minutes, scraping browned bits, until flavors meld. Remove from heat and stir in chopped parsley and optional 1 tsp lemon juice. Taste and adjust seasoning. Keep warm or bring to room temperature for assembling.

In a small saucepan, melt butter or warm olive oil over medium heat. Add minced shallot and smashed garlic, sauté 2–3 minutes until softened and aromatic but not browned.

Add red wine (if using) and simmer 1 minute to reduce slightly. Stir in mushroom or vegetable stock, soy sauce, and 1 tsp tomato paste. Add thyme sprig and bay leaf. Bring to a simmer and let reduce gently 8–10 minutes to concentrate flavor.

Remove thyme sprig and bay leaf. Taste and season with salt and black pepper. If a slightly thicker coating is desired, whisk a cornstarch slurry (1 tsp cornstarch mixed with 1 tbs cold water) into the simmering jus and cook 1 minute until slightly thickened. Keep warm until serving.

Make sure the au jus is warm and the cheese on the sandwich is melted. Plate sandwiches with a small bowl or ramekin of warm au jus on the side for dipping. Serve immediately.