Crispy Panko-Stuffed Portobello Mushroom Sandwiches with Smoky Mustard Sauce

These portobello mushroom sandwiches are a hearty, vegetarian twist on a classic comfort food. Thick portobello caps are stuffed with gooey mozzarella and topped with a crispy panko crust, then roasted until tender and golden. The smoky mustard sauce adds a tangy kick that perfectly complements the rich mushrooms and melted cheese.

Served on soft brioche buns with fresh tomato and crispy fried onions and paired with a simple ranch-dressed side salad, this meal is both satisfying and full of flavor. It’s an easy oven-baked dinner that comes together in under an hour with minimal prep.

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Ingredients

0.5 cup Panko BreadcrumbsView ingredient guideLike ingredientDislike ingredient

1 tablespoon Fry SeasoningView ingredient guideLike ingredientDislike ingredient

1 unit Oven-Ready TrayView ingredient guideLike ingredientDislike ingredient

2 ounce Smoky MustardView ingredient guideLike ingredientDislike ingredient

4 ounce Mixed GreensView ingredient guideLike ingredientDislike ingredient

0.5 cup Mozzarella CheeseView ingredient guideLike ingredientDislike ingredient

2 tablespoon MayonnaiseView ingredient guideLike ingredientDislike ingredient

2 unit Brioche BunsView ingredient guideLike ingredientDislike ingredient

1 unit TomatoView ingredient guideLike ingredientDislike ingredient

1 unit Crispy Fried OnionsView ingredient guideLike ingredientDislike ingredient

3 ounce Buttermilk Ranch DressingView ingredient guideLike ingredientDislike ingredient

2 unit Portobello MushroomsView ingredient guideLike ingredientDislike ingredient

4 ounce BaconView ingredient guideLike ingredientDislike ingredient

4 teaspoon (tsp) Olive OilView ingredient guideLike ingredientDislike ingredient

teaspoon (tsp) SaltView ingredient guideLike ingredientDislike ingredient

teaspoon (tsp) Black PepperView ingredient guideLike ingredientDislike ingredient

Instructions

1. Adjust rack to top position and preheat oven to 425°F. Wash and dry produce. Using a spoon, scrape out and discard the black gills from the underside of the portobello mushrooms. Trim any large stems if needed. Slice the tomato into ¼-inch-thick rounds.
2. Drizzle both sides of each mushroom with 2 teaspoons olive oil and rub to coat evenly. Season with half the Fry Seasoning, salt and pepper. Place mushrooms top-side down in an oven-safe tray. Sprinkle mozzarella cheese evenly over the mushrooms.
3. In a small bowl, combine panko breadcrumbs, remaining Fry Seasoning, a drizzle of olive oil, salt and pepper. Sprinkle the panko mixture over the mushrooms, pressing lightly to adhere. Tightly cover the tray with aluminum foil. Bake on the top rack until mushrooms are tender, 14-16 minutes.
4. Remove the foil and continue baking until the cheese and panko are golden brown, about 5 minutes more. Watch carefully to avoid burning.
5. While mushrooms bake, in another small bowl, mix mayonnaise and smoky mustard to make the sauce. Halve the brioche buns and toast them lightly.
6. In a large bowl, toss mixed greens with half the buttermilk ranch dressing. Season with salt and pepper.
7. Spread the cut sides of the buns with the smoky mustard sauce. Fill each bun with sliced tomato, a portobello mushroom and crispy fried onions. Divide sandwiches and salad between plates. Drizzle remaining dressing over the salad if desired. Serve immediately.

Recipe Tips

FAQ

Can I use a different type of mushroom?

Portobello mushrooms are ideal for their large size and meaty texture, but you can substitute with large cremini mushrooms if needed. Adjust cooking time accordingly.

How do I make this recipe gluten-free?

Use gluten-free panko breadcrumbs and ensure your brioche buns are gluten-free. Check all other ingredients for gluten.

Can I prepare the mushrooms ahead of time?

You can prep the mushrooms (remove gills, season and stuff) up to a day in advance. Store covered in the refrigerator and bake just before serving.