Quick Recipe Version (TL;DR)
Quick Ingredients
- 4 large portobello mushroom caps (about 4–5 inches wide)
- 1/2 cup BBQ sauce
- 2 tbsp balsamic vinegar
- 1 tbsp soy sauce (or tamari)
- 2 tbsp olive oil
- 2 tsp smoked paprika
- 2 garlic cloves, grated or minced
- 1/2 tsp kosher salt, plus more to taste
- 1/4 tsp black pepper
- 2 cups shredded green cabbage
- 1 cup shredded purple cabbage
- 1 medium carrot, grated (about 3/4 cup)
- 1/3 cup mayonnaise
- 1 tbsp apple cider vinegar
- 2 tsp Dijon mustard
- 1 tsp sugar
- 4 burger buns
- 4 slices smoked provolone (or cheddar)
Do This
- 1. Mix slaw dressing (mayo, vinegar, Dijon, sugar, salt/pepper) and toss with cabbages + carrot; chill.
- 2. Whisk BBQ, balsamic, soy sauce, olive oil, smoked paprika, garlic, salt, and pepper.
- 3. Marinate portobellos gill-side up in the sauce for 30 minutes (flip halfway).
- 4. Preheat grill to 475°F (medium-high) and oil the grates.
- 5. Grill mushrooms 4–5 minutes per side, basting with leftover marinade, until juicy with char lines.
- 6. Top each with cheese; close lid 1 minute to melt. Toast buns 30–60 seconds.
- 7. Assemble: bun + mushroom “BBQ steak” + crunchy slaw (and extra BBQ if you want).
Why You’ll Love This Recipe
- Big “steakhouse” vibes without the meat: smoky, saucy, and satisfying.
- Portobellos stay juicy on the grill and pick up gorgeous char lines fast.
- Crunchy slaw balances the rich BBQ glaze and melted cheese.
- Easy to scale up for cookouts, and most parts can be prepped ahead.
Grocery List
- Produce: 4 large portobello mushroom caps, green cabbage, purple cabbage, 1 carrot, 2 garlic cloves (optional: pickles, cilantro)
- Dairy: 4 slices smoked provolone (or cheddar/pepper jack)
- Pantry: BBQ sauce, balsamic vinegar, soy sauce (or tamari), olive oil, smoked paprika, kosher salt, black pepper, mayonnaise, apple cider vinegar, Dijon mustard, sugar, 4 burger buns
Full Ingredients
Portobello “BBQ Steak”
- 4 large portobello mushroom caps (about 4–5 inches wide)
- 1/2 cup BBQ sauce
- 2 tablespoons balsamic vinegar
- 1 tablespoon soy sauce (or tamari)
- 2 tablespoons olive oil
- 2 teaspoons smoked paprika
- 2 garlic cloves, finely grated or minced
- 1/2 teaspoon kosher salt
- 1/4 teaspoon black pepper
Crunchy Slaw
- 2 cups shredded green cabbage
- 1 cup shredded purple cabbage
- 1 medium carrot, grated (about 3/4 cup packed)
- 1/3 cup mayonnaise
- 1 tablespoon apple cider vinegar
- 2 teaspoons Dijon mustard
- 1 teaspoon sugar
- 1/4 teaspoon kosher salt, plus more to taste
- 1/8 teaspoon black pepper
For Serving
- 4 burger buns (brioche, potato, or whole wheat)
- 4 slices smoked provolone (or sharp cheddar or pepper jack)
- 1 tablespoon neutral oil for the grill grates (canola, avocado, or grapeseed)
- Optional: extra BBQ sauce for drizzling
- Optional: dill pickle chips or quick pickled onions
Step-by-Step Instructions
Step 1: Make the slaw and chill it
In a medium bowl, whisk together the mayonnaise, apple cider vinegar, Dijon mustard, sugar, kosher salt, and black pepper until smooth.
Add the green cabbage, purple cabbage, and grated carrot. Toss until everything is evenly coated. Cover and refrigerate for at least 20 minutes while you marinate and grill the mushrooms. (This short chill time helps the cabbage soften slightly while staying crunchy.)
Step 2: Clean and prep the portobellos
Gently wipe the portobello caps with a damp paper towel to remove any dirt. If the stems are attached, twist them off. Using a spoon, scrape out the dark gills (optional, but it helps the marinade soak in and keeps the sandwich from looking muddy).
Lightly score the top of each cap (the rounded side) with 2–3 shallow cuts in a crosshatch pattern, about 1/8-inch deep. This helps the marinade penetrate and encourages better charring.
Step 3: Mix the smoky BBQ-balsamic marinade
In a shallow dish (or a gallon zip-top bag), whisk together the BBQ sauce, balsamic vinegar, soy sauce, olive oil, smoked paprika, garlic, kosher salt, and black pepper.
Taste the marinade. If your BBQ sauce is very sweet, the balsamic and soy should balance it; if it tastes too sharp, add 1 teaspoon more BBQ sauce.
Step 4: Marinate the mushrooms
Place the portobellos in the dish gill-side up and spoon some marinade into the gill side. Flip them so they’re coated on both sides. Marinate for 30 minutes at room temperature, flipping once halfway through.
Food-safety note: Because this marinade touches raw mushrooms and then gets brushed on during grilling, reserve 2 tablespoons of marinade in a separate small bowl before adding the mushrooms if you want extra sauce for serving. Otherwise, plan to use fresh BBQ sauce for drizzling.
Step 5: Preheat the grill
Preheat a gas grill (or grill pan) to 475°F (medium-high). Clean the grates, then lightly oil them using a folded paper towel dipped in 1 tablespoon neutral oil (use tongs to avoid burns).
You’re looking for a hot grill so the mushrooms char quickly without turning soggy.
Step 6: Grill the portobellos until juicy with char lines
Remove mushrooms from the marinade, letting excess drip off (but don’t wipe them dry). Place them on the grill gill-side down first. Grill for 4–5 minutes, lid closed if using a grill.
Flip and grill another 4–5 minutes, basting with a little marinade as they cook. The mushrooms should be tender and juicy, with visible grill marks and a glossy BBQ glaze. (If your caps are extra large, they may need 1–2 minutes longer per side.)
Step 7: Melt the cheese and toast the buns
Reduce heat slightly if needed (aim to stay around 425–450°F), then place 1 slice cheese on each mushroom. Close the lid and grill for 1 minute, just until melted.
While the cheese melts, lightly toast the cut sides of the buns on the grill for 30–60 seconds. Watch closely; buns can go from golden to burnt quickly.
Step 8: Assemble the sandwiches
Place each cheesy portobello on the bottom bun. Pile on a generous handful of crunchy slaw (about 1/2 cup per sandwich). Add pickles or extra BBQ sauce if you like, then close with the top bun.
Serve right away while the mushrooms are hot and the cheese is melty.
Pro Tips
- Hot grill = better texture. A grill around 475°F gives you fast char and keeps the mushrooms meaty instead of watery.
- Scrape the gills for cleaner flavor. It’s optional, but it helps the marinade soak in and makes the sandwich look brighter.
- Don’t over-marinate. Stick to about 30 minutes. Too long in an acidic marinade (balsamic) can make mushrooms overly soft.
- Use a sturdy bun. Brioche, potato rolls, or toasted whole wheat hold up well against juicy mushrooms and slaw.
- Want extra smoky flavor? Add 1/4 teaspoon chipotle powder or 1/2 teaspoon liquid smoke to the marinade (optional).
Variations
- Spicy BBQ: Add 1 tablespoon minced chipotle in adobo (or 1 teaspoon hot sauce) to the marinade; use pepper jack cheese.
- Carolina-style slaw: Swap mayo for 2 tablespoons olive oil and increase apple cider vinegar to 3 tablespoons; add a pinch of celery seed.
- Loaded “steakhouse” version: Add caramelized onions and a swipe of horseradish mayo (2 tablespoons mayo + 1 teaspoon prepared horseradish).
Storage & Make-Ahead
Make-ahead: The slaw can be made up to 24 hours ahead and kept covered in the refrigerator. The marinade can be mixed up to 3 days ahead (refrigerate) and whisked again before using.
Store: Keep grilled mushrooms and slaw in separate airtight containers in the refrigerator for up to 3 days. Keep buns at room temperature.
Reheat: Warm mushrooms in a skillet over medium heat for 3–4 minutes per side, or in a 375°F oven for 8–10 minutes. Add cheese during the last minute of reheating. Assemble with cold slaw just before eating.
Nutrition (per serving)
Approximate per 1 sandwich (with bun, cheese, and slaw): 520 calories, 19 g protein, 22 g fat, 63 g carbohydrates, 8 g fiber, 14 g sugar, 980 mg sodium. Values vary by bun, BBQ sauce, and cheese brands.
