Portobello Mushroom Sandwich with Smoky Ranch Slaw

This juicy portobello mushroom sandwich is layered with creamy avocado and crunchy smoky ranch slaw for a hearty vegetarian dinner that's ready in 25 minutes. No grill or marinade required, with easy grill, oven, and air fryer options included

As someone who cooks mostly vegetarian meals at home, I'm always looking for sandwiches that feel hearty enough for dinner - and portobello mushrooms are one of the best ways to get that meaty, savory bite without using meat. For this portobello mushroom sandwich, I pan-sear the mushrooms until juicy and tender, then layer them with creamy smashed avocado and a crunchy smoky ranch slaw for contrast.

Unlike many portobello sandwich recipes, this version doesn't require a long marinade or a grill, so it's easy enough for a weeknight but still satisfying enough for a summer cookout. I've also included grill, oven, and air fryer options below.

For more vegetarian sandwich recipes, try my vegetarian BLT sandwich, bbq tofu sandwich with crunchy slaw, and mushroom and lentil sloppy joes!

Jump to:

• ⭐️ Why You'll Love This Portobello Mushroom Sandwich
• 🍄 How To Prep Portobello Mushrooms
• 🥪 Ingredient Notes
• 🔪 How to Make Portobello Mushroom Sandwich
• Alternative Cooking Methods: Grill, Oven, or Air Fryer
• 👩🏼‍🍳 Expert Tips for Juicy Portobello Sandwiches
• Storage & Make-Ahead Tips
• What To Serve with Portobello Mushroom Burgers
• 🍽 More Vegetarian Sandwich Recipes
• Portobello Mushroom Sandwich Recipe

⭐️ Why You'll Love This Portobello Mushroom Sandwich

• Hearty and satisfying: Portobello mushrooms have a naturally meaty texture, making this a filling vegetarian sandwich even meat-eaters will enjoy.
• No grill required: The mushrooms cook quickly in a skillet, with easy grill, oven, and air fryer options included.
• Big flavor and texture: Juicy mushrooms, creamy avocado, and crunchy smoky ranch slaw make every bite balanced.
• Ready in 25 minutes: A fast vegetarian dinner or casual weekend lunch.
• Easy to customize: Make it vegan, gluten-free, extra saucy, or double-stacked depending on what you have.

🍄 How To Prep Portobello Mushrooms

Gently wipe the mushroom caps clean with a damp towel instead of rinsing them, since mushrooms absorb moisture easily. Remove the stems, then scrape out the gills with a spoon if you prefer a cleaner look or want to reduce excess moisture. Brush the caps with olive oil and season before cooking so they brown nicely and stay juicy.

🥪 Ingredient Notes

• Portobello mushrooms - Look for large, firm mushroom caps that are similar in size so they cook evenly. Wipe them clean with a damp towel and remove the stems before cooking.
• Olive oil: Helps the mushrooms brown and keeps them juicy. Avocado oil also works.
• Mayonnaise - Makes the slaw creamy. Use vegan mayo to keep the sandwich vegan/dairy-free.
• Buttermilk - Gives the ranch slaw its tangy flavor. For a vegan option, use your favorite unsweetened dairy-free milk with a small splash of lemon juice or vinegar.
• Ranch slaw seasoning: The seasoning for our ranch coleslaw is a mixture of dried dill, dried parsley, dried chives, onion powder and garlic powder.
• Shredded carrots and cabbage - Adds fresh flavor, crunch, and a pop of color.
• Avocado: Adds creaminess and makes the sandwich more filling. Guacamole also works well here.
• Buns - Use sturdy buns or rolls to help soak up all of the juiciness of the sandwich. Brioche buns, pretzel rolls, or ciabatta rolls all work great. Use gluten-free buns if needed.

🔪 How to Make Portobello Mushroom Sandwich

Make the mushrooms:

Wipe the mushrooms clean and remove the tough stems. Preheat a large skillet to medium heat, and add olive oil to skillet.

Working in two batches, sprinkle 2 mushrooms with a pinch of salt and place into skillet with gills facing up. Cook 4-5 minutes, then flip over and cook for an additional 5 minutes, until the mushrooms are firm-tender. Repeat with the remaining 2 mushrooms.

Make the ranch slaw:

Meanwhile, in a medium bowl, whisk together mayonnaise, buttermilk, vinegar, dill, parsley, chives, onion powder, garlic powder, and salt. Add shredded carrots and cabbage and stir until both are completely covered in sauce.

Assemble sandwiches:

To assemble sandwiches, smash ¼ of avocado (if using) on top half of a hamburger bun. Place cooked mushroom on bottom half of bun and add a generous scoop of the slaw on top. Serve immediately.

Alternative Cooking Methods: Grill, Oven, or Air Fryer

• Skillet: Best for a quick weeknight sandwich and the method used in this recipe.
• Grill: Brush with oil and grill for about 8-10 minutes, flipping once, until tender.
• Oven: Bake at 350ºF for about 15 minutes, or until tender.
• Air fryer: Cook at 375ºF for 7-10 minutes, gill-side up, until juicy and tender.

👩🏼‍🍳 Expert Tips for Juicy Portobello Sandwiches

• Wipe the mushrooms clean with a damp or dry towel instead of rinsing them under water; excess moisture can make them cook up softer.
• Remove the woody stems if they feel tough. The gills are edible, but you can scrape them out if you prefer a cleaner look and less moisture.
• Cook the mushrooms until tender but not collapsed; they should still hold their shape inside the bun.
• Use sturdy buns like brioche, pretzel rolls, or ciabatta so the sandwich holds up to the juicy mushroom and slaw.
• Assemble right before serving so the bun stays crisp and the slaw keeps its crunch.

Storage & Make-Ahead Tips

• Refrigerator: Store cooked portobello mushrooms in an airtight container in the refrigerator for up to 4 days.
• Slaw: Store the smoky ranch slaw separately in an airtight container for up to 2 days. Stir before serving, as it might release some liquid as it sits.
• Avocado: For best texture and color, slice or mash the avocado right before assembling.
• Reheating: Warm the mushrooms in a skillet over medium-low heat or in the microwave until heated through.
• Make-ahead tip: You can prep the slaw and clean the mushrooms ahead of time, but wait to cook the mushrooms and assemble the sandwiches until just before serving.
• Freezing: I don't recommend freezing this sandwich, as the mushrooms, slaw, and avocado can all become mushy or watery after thawing.

What To Serve with Portobello Mushroom Burgers

Serve these sandwiches paired with corn on the cob, summer watermelon salad, mashed potatoes, vegetarian baked beans, or sweet potato fries.

Serve with your favorite toppings and condiments. You can skip the slaw altogether and use mayo, mustard, lettuce, tomato, or basil aioli instead.

🍽 More Vegetarian Sandwich Recipes

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