Ingredients

Equipment Needed

• •Charcoal or gas grill
• •Wide metal spatula
• •Long-handled tongs
• •Wire grill brush
• •Shallow baking dish for marinating

Instructions

1. 1

   Clean the portobellos

   Wipe each mushroom cap with a damp paper towel to remove any grit. Do not rinse them under water. Mushrooms are sponges, and waterlogged caps will steam on the grill instead of developing proper char. Use a spoon to gently scrape out the dark gills from the underside. This isn't strictly necessary, but the gills hold excess moisture and can give the finished dish a muddy appearance. You want clean, bowl-shaped caps ready to receive the marinade.

   Select caps that are firm with dry surfaces. Avoid any that feel slimy or have darkened, wet spots.
2. 2

   Make the marinade

   Whisk together the olive oil, balsamic vinegar, minced garlic, salt, and pepper in a small bowl. The balsamic brings sweetness that will caramelize beautifully over the flames. Place the mushroom caps gill-side up in a shallow baking dish or rimmed sheet pan. Spoon the marinade into the cavity of each cap, letting it pool there. Reserve about two tablespoons of marinade for basting. Let the mushrooms sit at room temperature for twenty minutes while you prepare the chimichurri and heat your grill.

3. 3

   Prepare the chimichurri

   Combine the parsley, oregano, and roughly chopped garlic on your cutting board. Run your knife through them until finely minced but not pureed. You want texture here, not paste. Transfer to a bowl and stir in the olive oil, red wine vinegar, red pepper flakes, salt, and pepper. The sauce should be loose and spoonable, bright green flecked with red. Taste it. The vinegar should be assertive, the garlic present but not punishing. Adjust the salt if needed. Set aside at room temperature.

   A food processor works but tends to bruise the herbs. Hand-chopping takes three extra minutes and produces a superior sauce with better color and cleaner flavor.
4. 4

   Heat your grill

   Prepare a charcoal grill for direct high heat, banking all coals to one side for a two-zone fire. If using gas, preheat with all burners on high for ten minutes, then reduce one side to medium. You want the hot zone around 450 to 500 degrees. Clean the grates thoroughly with a wire brush and oil them by dipping a folded paper towel in vegetable oil, gripping it with long tongs, and rubbing it across the hot grates. This prevents sticking and promotes those beautiful grill marks.

5. 5

   Grill the portobellos

   Place the mushroom caps gill-side up on the hottest part of the grill. Listen for the sizzle. If there's no sound, your grill isn't hot enough. Close the lid and let them cook undisturbed for four to five minutes. The edges will begin to soften and curl slightly, and you'll see grill marks developing underneath. Flip the caps using a wide spatula. Brush the now-exposed tops with the reserved marinade. Grill gill-side down for another three to four minutes until tender when pierced with a knife and deeply charred on both surfaces.

   Resist the urge to press down on the caps. You'll squeeze out moisture and lose juiciness. Let the grill do its work.
6. 6

   Rest and serve

   Transfer the grilled portobellos to a cutting board and let them rest for two minutes. The residual heat will finish cooking the centers while the exterior cools enough to handle. Slice each cap on the bias into thick strips, or serve whole for a more dramatic presentation. Arrange on a warm platter and spoon the chimichurri generously over the top, letting it pool around the edges. The bright green sauce against the dark, charred mushrooms is a thing of beauty. Serve immediately while the mushrooms are still warm and the herbs are vibrant.

Chef Tips

• •The best portobellos come from farmers' markets where turnover is high and the mushrooms haven't sat in plastic wrap for days. Look for caps that are firm with closed edges. If the gills are exposed and spreading, the mushroom is past its prime.
• •Chimichurri improves over the first hour as the flavors meld, but it dulls after twenty-four hours as the herbs oxidize. Make it fresh for the best color and punch. Store leftovers in an airtight container with plastic wrap pressed directly against the surface.
• •If rain threatens your cookout, these portobellos cook beautifully on a cast iron grill pan over high heat indoors. You'll sacrifice some smoke flavor but none of the char.
• •Serve alongside grilled corn on the cob and a tomato salad dressed with good olive oil. Add crusty bread to soak up the chimichurri that escapes onto the plate. A cold Argentinian Malbec or a crisp Grüner Veltliner both complement the earthy mushrooms and bright herb sauce.

Advance Preparation

• •Chimichurri can be made up to 4 hours ahead and stored at room temperature. Press plastic wrap directly against the surface to prevent oxidation.
• •Mushrooms can be cleaned and gills removed up to a day ahead. Store in a paper bag in the refrigerator. Do not marinate until ready to grill.
• •The marinade can be whisked together the morning of your cookout and refrigerated. Bring to room temperature before using.

Frequently Asked Questions

Nutrition Information

1 serving (about 235g)