Portobello Sandwich Recipe

Prepare marinade

In a shallow dish or bowl, whisk together 1/4 cup olive oil, 2 tablespoons balsamic vinegar, 1 tablespoon soy sauce, 2 teaspoons minced garlic, 1 teaspoon dried oregano, 3 teaspoons salt, and 1 teaspoon black pepper until combined.

Clean mushrooms

Gently wipe the portobello caps with a damp paper towel to remove dirt. Remove and discard the stems if desired. Using a spoon, gently scrape out the gills if you prefer a milder flavor (optional).

Marinate mushrooms

Place the mushrooms gill-side down in the marinade, then spoon some marinade over the tops. Let marinate at room temperature for 20 minutes or refrigerate for up to 2 hours. Turn once halfway through to coat both sides.

Preheat grill or skillet

Heat a grill or heavy skillet (cast-iron) to medium-high heat (about 400°F / 200°C). Lightly oil the grates or skillet.

Grill portobellos

Brush excess marinade off the mushrooms and place gill-side down on the hot grill or skillet. Cook 4–5 minutes until marked and slightly charred, then flip and cook another 3–4 minutes until tender but still intact. If mushrooms are thick, close a lid or tent with foil for 1–2 minutes to ensure tenderness.

Warm peppers, artichokes, and onions

While mushrooms rest, briefly warm the roasted red peppers and marinated artichoke hearts in the skillet or on the grill for 1–2 minutes to heat through. Toss the thinly sliced red onion in the skillet for 30–45 seconds just to soften slightly and take off raw bite (optional).

Melt provolone

Return mushrooms to the grill or skillet, place a slice of provolone on each mushroom cap, and cover or tent for 30–60 seconds until cheese softens and begins to melt.

In a small bowl, combine 1/2 cup mayonnaise, 2 teaspoons prepared basil pesto, 1 teaspoon lemon juice, 1/4 teaspoon salt, and 1/8 teaspoon black pepper. Whisk until smooth and adjust seasoning to taste. Refrigerate until assembly.

Toast rolls

Brush cut sides of the ciabatta rolls with 1 tablespoon olive oil and sprinkle lightly with 1/4 teaspoon salt. Toast on the grill or in a skillet cut-side down for 1–2 minutes until golden and slightly crisp.

Assemble sandwich

Spread about 1 tablespoon pesto aioli on both the top and bottom halves of each toasted roll. Place the provolone-topped portobello on the bottom half, then top with warmed roasted red peppers, marinated artichoke quarters, and a handful (about 1/2 cup) of spring greens. Add the top roll and press gently.

Serve

Slice each sandwich in half if desired and serve immediately while warm. Leftover marinade can be discarded. Any remaining pesto aioli can be refrigerated for up to 3 days.