Grilled portobello mushrooms are a flavorful summertime vegetarian side dish. I marinate the caps first, then quickly cook them on the grill to infuse a rich and smokey taste.
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As the weather warms up, the grill gets fired up and cracked open. Portobello mushrooms offer a hearty vegetarian option to pair with the mains dishes to create a complete feast. The large fungi can get a little tough on the surface when cooked. I’ll show you how to prepare each piece for the most tender results.
To enhance the taste of the meaty caps, I marinate them in a savory balsamic vinegar mixture. This brief period boosts the natural umami notes, creating juicy bites that may outshine the other dishes. A quick sizzle on the barbecue or grill pan, and you’ll have a tasty vegetarian side dish, or you can easily make them into a mushroom burger.
Prepare the mushrooms
Trim or altogether remove the stem from the mushroom. It’s very thick and fibrous, and it helps to flatten the cap so that it can sit with even exposure on the grill. The underside of the cap contains soft brown gills. Although edible, they have a slight muddy flavor.
To remove the gills, use a spoon and lightly scrape it out. You’ll find it releases relatively easy. Wipe the surface with a damp paper towel to clean, or a quick rinse and dry well. Just don’t let the mushrooms soak in water, or it will absorb that liquid instead of the flavorful marinade.
Score the cap for better texture
Portobello mushrooms are large, about 4 to 6 inches in diameter. This size makes it ideal for placing on the grill and keeping its form once cooked. Since the caps aren’t sliced into smaller pieces, the surface can get a bit chewy. To tenderize the mushroom caps, score a shallow cross-hatch pattern on the top. This technique helps break up the surface layer and absorb more of the marinade.
Marinate the mushrooms
Before grilling, the cleaned and prepared caps get a dip in a soy sauce and balsamic vinegar marinade. Freshly minced garlic adds some additional zing. However, I recommend using garlic powder if cooking on a grill pan to prevent the pieces from burning.
Olive oil adds richness and helps to prevent sticking to the grates. The savory sauce enhances the natural umami flavor in the mushrooms, while the acidity in the vinegar provides balance and brightness. You’ll notice that after a 30-minute soak, the mixture gets absorbed into the caps. The result, super juicy and flavorful pieces!
You can grill the caps outdoor on a barbecue or indoors in the grill pan. The first option provides a deeper smokey taste, while the pan gives an all-season alternative that cooks quicker due to the smaller cooking area and consistent heat.
No matter which method you choose, make sure to start with the gill-side facing up. This method captures more flavor into the meaty part of the cap and achieves the sought-out charred lines. Flip over to finish the cooking process. It goes fast!
Serve this with
Should mushrooms be washed?
Yes, mushrooms should get a gentle wipe with water and a paper towel or a brief rinse to remove the excess dirt. They luckily have a protein called hydrophobins on the surface of the cap that repels water. Although, if soaked too long, the fungi act like sponges absorbing moisture. The large brown gills on portobellos also like to soak up liquid, which is why we remove them first before cleaning. We want the mushrooms to infuse the marinade instead of plain water.
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Grilled Portobello Mushrooms
- Prepare the mushrooms by cutting off the stems, then use a spoon to scoop out the brown gills. Use a damp paper towel to clean any dirt off the surface gently.
- Use the tip of a paring knife to cut a ½-inch crosshatch pattern on the tops of the mushroom caps, about 1/16-inch deep scores.
- In a small bowl, whisk together olive oil, balsamic vinegar, soy sauce, minced garlic, salt, pepper, and garlic powder.
- Add mushrooms to a large plastic bag or baking dish. Turn to coat in the marinade and allow to sit for 30 to 60 minutes.
- Barbecue Cooking: Preheat grill over medium-high heat 350 to 400ºF (177 to 204ºC). Clean the grill and carefully grease the cooking grates with tongs and a paper towel dipped in oil. Remove the mushrooms from the marinade, then place it on the hot grill, cap-side down. Cover and cook, 4 to 6 minutes. Flip and cook covered for 3 to 5 minutes.Grill Pan Cooking: Cook mushrooms on a grill pan heated over medium-high heat. Grease the grates with oil, then cook for 4 to 5 minutes. Flip and cook until mushrooms are tender, about 2 to 3 minutes.
- Grill Pan cooking: I recommend using garlic powder instead of fresh minced garlic as the pieces will burn in the hot pan. Increase garlic powder to 1/2 teaspoon.
- Make it Gluten-Free: Substitute coconut aminos, gluten-free tamari, or liquid aminos instead of soy sauce.
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