If you’re looking for a hearty, plant‑based alternative to steak, these Garlic‑Butter Marinated & Grilled Portobello Steaks are the perfect choice.
Meaty portobello mushroom caps are marinated in a rich garlic‑butter sauce, then grilled until tender and smoky.
They’re flavorful, satisfying, and ideal for serving as a vegetarian main dish or alongside your favorite grilled sides. This recipe quickly became a favorite in our home because it’s easy, full of flavor, and feels indulgent while still being light and wholesome.
Whether you’re vegetarian, trying to cut back on meat, or just love mushrooms, this dish is a winner.
Why You’ll Love This Recipe
These Garlic‑Butter Marinated & Grilled Portobello Steaks are smoky, juicy, and packed with umami flavor.
The garlic‑butter marinade seeps into the mushrooms, giving them a rich, savory taste that pairs perfectly with grilled veggies, mashed potatoes, or a fresh salad.
They’re quick to prepare, naturally gluten‑free, and can be served as a main dish for vegetarians or as a hearty side for meat‑lovers. Ready in under 30 minutes, they’re a fantastic addition to any summer cookout or weeknight dinner.
What You’ll Need
- 4 large portobello mushroom caps
- 3 tablespoons olive oil
- 3 tablespoons melted butter (or vegan butter)
- 3 cloves garlic, minced
- 2 tablespoons soy sauce or tamari
- 1 tablespoon balsamic vinegar
- 1 teaspoon fresh thyme leaves (or ½ teaspoon dried thyme)
- ½ teaspoon black pepper
- ¼ teaspoon salt
- Lemon wedges (for serving)
Pro Tips
- Remove stems and gills to create a clean, steak‑like texture.
- Marinate for at least 15 minutes so the mushrooms soak up maximum flavor.
- Grill over medium heat to prevent burning while ensuring even cooking.
- Baste with extra marinade as they grill for more flavor.
- Rest before slicing to let juices settle, just like a real steak.
Tools You’ll Need
- Mixing bowl or shallow dish
- Whisk or fork
- Grill or grill pan
- Tongs
- Basting brush
Substitutions and Variations
- Vegan version: Use plant‑based butter.
- Extra flavor: Add smoked paprika or red pepper flakes to the marinade.
- Herb swap: Try rosemary or parsley instead of thyme.
- Asian‑inspired twist: Use sesame oil and a splash of rice vinegar instead of balsamic.
Make‑Ahead Tips
- Prepare the marinade up to 3 days in advance and store in the fridge.
- Clean and trim mushrooms ahead of time, storing them in the fridge in a paper towel‑lined container.
- Marinate mushrooms for up to 1 hour before grilling for extra flavor.
How to Make Garlic‑Butter Marinated & Grilled Portobello Steaks
1. Make the Marinade
In a bowl, whisk together olive oil, melted butter, garlic, soy sauce, balsamic vinegar, thyme, salt, and pepper.
2. Prepare the Mushrooms
Clean portobello caps with a damp cloth. Remove stems and gently scrape out the gills with a spoon.
3. Marinate the Mushrooms
Place the mushrooms gill‑side up in a shallow dish. Brush or spoon the marinade over each cap, then flip and coat the other side. Let marinate for at least 15–30 minutes.
4. Preheat the Grill
Heat a grill or grill pan over medium heat. Lightly oil the grates to prevent sticking.
5. Grill the Mushrooms
Place mushrooms gill‑side down on the grill. Cook for 4–5 minutes, basting occasionally. Flip and cook another 3–4 minutes, brushing with more marinade.
6. Serve
Remove from the grill, let rest for 2 minutes, and finish with a squeeze of lemon juice. Serve whole or sliced.
Leftovers and Storage
Store leftover mushrooms in an airtight container in the fridge for up to 3 days. Reheat in a skillet or grill pan for the best texture.
Avoid freezing, as mushrooms can release excess moisture when thawed.
Nutrition & Benefits
Portobello mushrooms are low in calories yet rich in antioxidants, fiber, and B vitamins.
The garlic and olive oil provide heart‑healthy fats and anti‑inflammatory compounds, making this dish both flavorful and nourishing.
Recipe FAQ
1. Can I cook these in a skillet instead of a grill?
Yes! A grill pan or cast‑iron skillet works perfectly—just cook for the same amount of time.
2. How long should I marinate the mushrooms?
At least 15 minutes, but up to 1 hour for deeper flavor.
3. Do I have to remove the gills?
It’s optional, but removing them gives a cleaner look and reduces bitterness.
4. Can I make this recipe vegan?
Yes! Use vegan butter or all olive oil.
5. What can I serve these with?
They pair beautifully with mashed potatoes, grilled veggies, or even sliced over a salad.
Juicy, Flavorful, and Perfectly Smoky
These Garlic‑Butter Marinated & Grilled Portobello Steaks are hearty, savory, and easy to make.
Whether you’re vegetarian or just want a flavorful side, they’re a satisfying addition to any meal.