Grilled Portobello Burgers with Chimichurri
Meaty marinated portobello caps are grilled until tender and smoky, then piled onto toasted buns with melted provolone, sweet roasted red pepper and a bright, garlicky Argentinian parsley chimichurri.
Steps
Before you start
- Make the chimichurri first; it rests while the mushrooms marinate, which lets the flavors meld.
- Do not wash the mushrooms under running water; they soak it up and turn soggy. Wipe them with a damp paper towel.
- Start preheating the grill about 10 minutes before the marinating time ends.
- Pat the jarred roasted red peppers very dry so they don't make the buns soggy.
Make the chimichurri
- In a small bowl, stir together the parsley, oregano, garlic, red wine vinegar, extra-virgin olive oil, red pepper flakes and kosher salt.
- Taste and add a pinch more salt if it tastes flat.
- Set aside at room temperature while you prep and marinate the mushrooms.
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Ready when: Herbs look glossy and fully coated in oil
Tip: Chop by hand; a food processor turns the herbs into a paste and dulls the texture.
Prep the mushrooms
- Twist out the stems and discard or save for stock.
- Wipe each cap with a damp paper towel.
- Use a spoon to gently scrape out the dark gills, which keeps the burgers from turning muddy and wet.
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Ready when: Caps are clean with a smooth, hollow underside
Tip: Scrape lightly so you don't tear the cap.
Marinate the caps
- In a small bowl whisk the olive oil, balsamic vinegar, soy sauce, minced garlic and black pepper.
- Place the caps gill-side up in a 9×13-inch (23×33 cm) dish and spoon the marinade over them so it pools in the hollows.
- Flip and brush the tops.
- Let sit 20 minutes at room temperature, flipping once halfway.
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Ready when: Caps look darker and glossy, with most of the marinade absorbed
Tip: Don't marinate longer than 30 minutes or the caps get soft and watery.
Preheat the grillOven 425°F / 220°C
- During the last 10 minutes of marinating, heat the grill to medium-high, about 400–425°F (205–220°C).
- Scrape the grates clean and wipe with an oiled paper towel held in tongs.
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Ready when: You can hold your hand 5 inches above the grate for only 3–4 seconds
Tip: A hot, oiled grate prevents sticking.
Grill the mushrooms
- Place the caps gill-side down on the grill and cook 5 minutes without moving, until deep grill marks form.
- Flip, brush with any remaining marinade, and cook 4–5 minutes more with the lid closed.
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Ready when: Caps are browned, slightly shrunken, a knife slides in easily and juices pool in the cap
Tip: Don't press down; pressing squeezes out the juices and dries the burger.
Melt the cheese
- Turn the caps gill-side up.
- Top each with a slice of provolone and a few strips of roasted red pepper.
- Close the grill lid and cook 1–2 minutes.
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Ready when: Cheese is fully melted and starting to droop over the edges
Tip: Dry the peppers well so they don't slide off.
Toast the buns
- Move the caps to a plate.
- Place the buns cut-side down on the grill for about 1 minute.
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Ready when: Cut sides are golden with light grill marks
Tip: Watch closely; buns burn in seconds.
Assemble and serve
- Stir the chimichurri.
- Spoon 1 tablespoon on each bottom bun, add arugula if using, set a cheesy mushroom cap on top, then spoon on 1–2 more tablespoons of chimichurri.
- Add the top bun and serve right away with extra chimichurri on the side.
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Tip: Stir the chimichurri before spooning so you get herbs, not just oil.
Good to know
Tips
- Choose caps of similar size and thickness so they finish cooking at the same time.
- Gill-side down first gives the best sear and traps juices when flipped.
- Use a grill pan over medium-high heat if you don't have an outdoor grill; cook the same times.
- Add a splash of lemon juice to the chimichurri just before serving if it needs more brightness.
Make ahead
Make the chimichurri up to 3 days ahead and refrigerate in a covered container; bring to room temperature before serving. Mushrooms can marinate in the fridge for up to 1 hour.
Storage & reheating
Assembled burgers are best eaten immediately. Store leftover grilled caps and chimichurri separately in airtight containers in the fridge for up to 3 days. Reheat caps in a 350°F (175°C) oven or skillet for 5 minutes. Chimichurri freezes up to 2 months; thaw in the fridge. Cooked caps don't freeze well.
Substitutions
- provolone cheese → Mozzarella, fontina or Swiss cheese. Use the same number of slices; any good melting cheese works.
- red wine vinegar → Sherry vinegar or fresh lemon juice. Use the same amount for similar brightness.
- soy sauce → Tamari or coconut aminos. Tamari keeps it gluten-free; use gluten-free buns too.
- burger buns or ciabatta rolls → Gluten-free buns or large lettuce leaves. Toast gluten-free buns gently as they brown faster.