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    Home » Recipes » Vegetarian » Portobello Mushroom and Spinach Subs

    By Amy · Published: Jan 7, 2022 · Updated: Jan 7, 2022 · This post may contain affiliate links. Please read my disclosure policy 4 Comments

    Portobello Mushroom and Spinach Subs

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    Three subs on a cutting board with overlay text that reads, "Portobello Mushroom and Spinach Subs".

    You’ll never miss the meat in these hearty and satisfying Portobello Mushroom and Spinach Subs. They’re a delicious weeknight dinner and prepared in just 30 minutes from start to finish!

    A closeup of three portobello mushroom subs on a wooden cutting board.

    If you’re a mushroom lover, you’re going to want to devour this savory sandwich. The marinade is a zesty and flavorful combination of red wine vinegar, Worcestershire sauce, spicy mustard, garlic, and olive oil. HEAVENLY.

    Ingredients Notes

    Overhead view of ingredients needed for making portobello mushroom subs.
    • Portobello mushrooms – wiped clean and debris removed with a damp towel, then cut into about 2-inch pieces.
    • Red onion – thinly sliced
    • Baby spinach – roughly chopped
    • Spicy mustard
    • Olive oil
    • Red wine vinegar
    • Worcestershire sauce
    • Garlic
    • Salt and black pepper
    • French baguette loaf – you can also use toasted bread, hamburger buns or sub rolls in place of the baguette… I love the texture of the crunchy baguette.
    • Shredded mozzarella – finely shredded Parmesan would be delicious, as well!

    How to Prepare

    Following is a brief overview of how to prepare – please see the recipe card at the bottom for full detailed instructions and ingredient amounts.

    A loaf baguette sliced into four pieces and vertically across the top on a cutting board.
    1. Slice a loaf baguette evenly into four slices, then slice vertically across the tops. Hollow each slice out, pulling out most of the bread inside. Set aside.
    Overhead view of marinade in a bowl with a whisk for portobello mushrooms.
    1. Whisk together red wine vinegar, Worcestershire, mustard, garlic and olive oil in a medium bowl.
    Two images of mushrooms and onions in marinade before and after sautéing.
    1. Place mushrooms and red onion slices in a large baking dish and pour the marinade over. Stir or toss to coat. Season with salt and pepper.
    2. Transfer mushroom mixture (along with the marinade) to a large skillet over medium high heat. Cook for five to six minutes, or until mushrooms are tender.
    A two-image collage of mushroom and spinach mixture and sliced baguette on a baking sheet.
    1. Transfer mushrooms and onions (with their marinade) back into the baking dish. Add spinach and stir well to combine, coating the spinach as evenly as possible. The spinach will wilt while your baguette is heating.
    2. Bake baguette slices on a baking sheet in a preheated oven for five minutes, or until warmed through. Carefully stuff each baguette piece with mushroom mixture and top with mozzarella.
    Overhead view of three portobello mushroom and spinach subs on a cutting board.

    Enjoy!

    More Delicious Mushroom Inspiration

    • Sautéed Mushrooms
    • Crab Stuffed Mushrooms
    • Portobello Caprese Pizzas
    • Cream of Mushroom Soup

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    Overhead view of three portobello subs on a wood cutting board.

    Portobello Mushroom and Spinach Subs

    You'll never miss the meat in these hearty and savory subs prepared in 30 minutes!
    5 from 1 vote
    Print Pin Rate
    Course: Vegetarian
    Cuisine: American
    Keyword: portobello mushroom and spinach subs
    Prep Time: 20 minutes
    Cook Time: 10 minutes
    Total Time: 30 minutes
    Servings: 4 subs
    Author: Amy

    Ingredients

    • 1 loaf baguette about 7 ounces
    • ¼ cup red wine vinegar
    • 1 tablespoon Worcestershire sauce
    • 2 tablespoons spicy mustard
    • 1 tablespoon minced fresh garlic
    • ½ cup extra virgin olive oil
    • 2 (6 ounce) packages portobello mushrooms wiped clean and debris removed with a damp towel, then cut into about 2 inch pieces
    • ½ cup thinly sliced red onion
    • ¼ teaspoon salt more or less, to taste
    • ¼ teaspoon black pepper more or less, to taste
    • 1 (5 ounce) package baby spinach roughly chopped
    • ½ cup shredded mozzarella cheese more or less, to taste

    Instructions

    • Preheat your oven to 350 degrees F. Slice baguette evenly into 4 slices. Slice vertically across each top and hollow each slice out, pulling out the bread inside. Set aside.
    • In a medium bowl, whisk red wine vinegar, Worcestershire sauce, mustard, garlic and olive oil.
    • Place mushrooms and red onion slices in a large baking dish and pour marinade over. Stir and/or toss to coat mushrooms and red onions evenly. Season with salt and pepper and set aside.
    • Transfer mushrooms and red onions in their marinade to a large skillet over medium-high heat (keep baking dish to transfer mushroom/onion mixture back into). Cook over medium-high heat for 5 to 6 minutes, stirring constantly, or until mushrooms are tender.
    • Transfer mushrooms and onions back into marinade dish. Add fresh chopped spinach and stir well to combine and coat spinach as evenly as possible. Spinach will wilt while your baguette is heating.
    • Place baguette slices onto a baking sheet and bake for approximately 5 minutes. Remove from oven and carefully stuff each baguette piece with mixture and top with shredded cheese. Serve immediately.

    Nutrition

    Calories: 499kcal | Carbohydrates: 40g | Protein: 12g | Fat: 33g | Saturated Fat: 6g | Polyunsaturated Fat: 4g | Monounsaturated Fat: 21g | Trans Fat: 1g | Cholesterol: 11mg | Sodium: 782mg | Potassium: 676mg | Fiber: 4g | Sugar: 4g | Vitamin A: 3428IU | Vitamin C: 13mg | Calcium: 176mg | Iron: 4mg

    If provided, nutritional info is a courtesy, is not guaranteed and should only be considered as a guideline.

    Tried this recipe?Mention @TheBlondCook or tag #theblondcook!

    Originally published January 2012. Updated with new text, new images and recipe slightly revised January 2022.

    Adapted from Food Network

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      Recipe Rating




    1. Kirsti says

      January 14, 2016 at 8:14 pm

      5 stars
      We made this tonight and it was delicious!

      Reply
      • Amy @ The Blond Cook says

        January 14, 2016 at 9:55 pm

        Thank you! So glad you enjoyed it Kirsti! 🙂

        Reply
    2. Maggie says

      May 21, 2014 at 8:01 pm

      Great recipes!!

      Reply
      • Amy @ The Blond Cook says

        May 22, 2014 at 7:03 am

        Thank you so much, Maggie!

        Reply

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