# Grilled King Oyster Mushroom 'Scallops' with Lemon-Caper Brown Butter on Crispy Sourdough > Thick-sliced king oyster mushrooms are caramelized over high heat to mimic seared scallops, finished with a bright lemon-caper brown butter and served on charred sourdough rounds. These elegant, vegetarian grilling bites are quick to make and perfect for parties or a show-stopping appetizer. Canonical URL: https://www.topshelf.recipes/recipes/grilled-king-oyster-mushroom-scallops-lemon-caper-brown-butter ## Author Jake Woods https://www.topshelf.recipes/chef/jake-woods Published: July 27, 2026 Last Updated: September 3, 2026 ## About This Recipe King oyster mushrooms have a dense, meaty stem that responds to high heat much like a scallop: when cut into 1-inch medallions and seared hard, they develop a deep, caramelized Maillard crust while remaining tender inside. I lean into that contrast here — a light cornstarch dusting encourages an almost shell-like crust, a soy-lemon marinade seasons the flesh without masking it, and a lemon-caper brown butter gives the sweet-and-acid lift we instinctively want with rich, unctuous bites. Serving them on charred sourdough rounds adds a crunchy, smoky platform that keeps the mushrooms from getting soggy and makes these perfect for passing around as elegant, handheld hors d’oeuvres. What makes this version work is attention to timing and balance: sear the medallions without fussing so they develop color, then finish briefly in nutty brown butter so they’re glossy but not steamed. The capers and lemon cut through the butter and echo classic seafood pairings, so vegetarians and omnivores alike find the experience familiar yet new. Make the brown butter ahead for easy party service, or double it to spoon over roasted vegetables or grilled fish another night. ## Recipe Information - Prep Time: 20 minutes - Cook Time: 15 minutes - Total Time: 35 minutes - Servings: 3 - Difficulty: Medium - Category: Grilling ## Ingredients ### Slice and marinate the mushrooms - 12 oz King oyster mushrooms (thick slices) - 3 tbsp Extra-virgin olive oil - 1 tbsp Fresh lemon juice - 1 tbsp Low-sodium soy sauce (or tamari) - 1/2 tsp Garlic powder ### Dust and grill for a scallop-like crust - 2 tsp Cornstarch (light dusting to encourage crust) - 8 slices Sourdough rounds (sliced to 2" rounds or use small slices) ### Make the lemon-caper brown butter - 4 tbsp Unsalted butter - 2 tbsp Capers (rinsed and drained) ### Finish the mushrooms in the brown butter - 1 cup Microgreens (for garnish) ## Ingredient Guide ### King oyster mushrooms (thick slices) A large, meaty mushroom (Pleurotus eryngii) native to East Asia and commonly used in Korean, Japanese, and Chinese cooking; it has a dense, meaty texture and mild umami flavor that can be slightly sweet and seafood-like when seared. You’ll find them at Asian markets, well-stocked supermarkets, or farmers’ markets. Good substitutes are thickly sliced portobello or large shiitake mushrooms, or other oyster mushroom varieties for a similar texture. ### Capers (rinsed and drained) Small pickled flower buds used widely in Mediterranean cuisine (especially Italian and Provençal) that add a bright, tangy, saline, and slightly floral burst to dishes. They’re sold jarred in brine in most grocery stores near olives and pickles. If you don’t have capers, chopped green olives, chopped cornichons/gherkins, or a squeeze of lemon with a pinch of salt can mimic the briny, acidic lift. ### Microgreens (for garnish) Very young vegetable or herb seedlings harvested just after the first leaves form; they’re a contemporary garnish used in fine-dining and modern home cooking and offer concentrated flavor that varies by variety (peppery, mustardy, sweet, or herbaceous). Sold in small clamshells at farmers’ markets, specialty produce sections, and some supermarkets. Substitute with baby greens, tender herb leaves (like parsley, cilantro, or basil), or sprouts for visual appeal and a fresh pop of flavor. ## Instructions ### 1. Slice and marinate the mushrooms Trim ends of king oyster mushrooms and slice crosswise into thick 1" rounds (about 8–10 medallions). In a bowl whisk olive oil, lemon juice, soy sauce and garlic powder; toss mushrooms to coat and let sit 10–15 minutes while you preheat the grill to high. (Season lightly with salt and pepper to taste if desired.) ### 2. Dust and grill for a scallop-like crust Preheat your grill for direct high heat (450–500°F / 230–260°C). Lightly dust both sides of the marinated rounds with cornstarch, brush sourdough rounds and mushroom medallions with a little additional olive oil, and oil the grates. Place mushrooms on the hottest part of the grill and sear 3–4 minutes per side without moving until deep caramelization forms; press gently with a spatula for full contact and rotate 90° halfway through each side for a crosshatch crust. Meanwhile char sourdough 30–45 seconds per side until crisp and marked. ### 3. Make the lemon-caper brown butter While the mushrooms grill, melt butter in a small stainless skillet over medium heat and cook until it foams and turns a golden-brown nutty aroma (watch closely — 2–4 minutes). Remove from heat and stir in the rinsed capers and 1 tsp fresh lemon zest plus 1 tbsp lemon juice for brightness; return to very low heat just to warm the sauce, then remove so it doesn't overbrown. ### 4. Finish the mushrooms in the brown butter Transfer the hot grilled mushroom rounds into the skillet with the brown butter and toss or spoon the sauce over them 20–30 seconds to glaze and absorb flavor (do this in batches to avoid crowding). This quick finishing step builds extra gloss and flavor without steaming the crust. ### 5. Assemble and serve party-friendly bites Place one grilled mushroom 'scallop' on each charred sourdough round, spoon a little lemon-caper brown butter over the top, and finish with a small cluster of microgreens. For party service, arrange on a platter with toothpicks, keep warm on a sheet pan in a 200°F (95°C) oven for up to 20 minutes, and make the brown butter ahead to rewarm gently just before serving. ## Nutrition Estimated nutrition per serving (2 mushroom 'scallops' on sourdough rounds): - Calories: 577 kcal - Protein: 15.3 g - Carbohydrates: 52.4 g - Fat: 34.9 g - Saturated Fat: 13.6 g - Trans Fat: 0 g - Fiber: 5.5 g - Sugar: 5.6 g - Added Sugars: 0 g - Cholesterol: 56 mg - Sodium: 659 mg - Potassium: 694 mg - Calcium: 59 mg - Iron: 5.3 mg - Vitamin D: 0 mcg ## Tips ### Pick firm stems Choose large, thick king oyster stems — they hold their shape and caramelize better than the caps or thinner mushrooms. ### Pat dry before searing Blot marinated rounds with paper towel so excess moisture doesn’t steam the surface; a dry surface promotes a better crust. ### High direct heat Sear on a very hot grill (450–500°F) and resist flipping until a deep brown forms to maximize the Maillard reaction. ### Light cornstarch dusting Dust both sides sparingly with cornstarch to encourage an even, scallop-like crust without a gummy coating. ### Finish briefly in butter Toss mushrooms in the warm brown butter for only 20–30 seconds so they glaze without losing their sear to steam. ## Variations and Substitutions ### Pan-seared indoors If you don’t have a grill, use a screaming-hot cast-iron skillet and follow the same dusting and searing method for equally good caramelization. ### Vegan brown butter Replace butter with equal coconut oil or vegan butter and add a pinch of smoked paprika; add lemon and capers after removing from heat to mimic the brown-butter flavor profile. ### Smoky chile twist Toss a pinch of smoked paprika or a few flakes of Aleppo/Chile de Árbol in the brown butter for a warm, smoky heat that complements the mushroom’s umami. ### Different bases Swap charred sourdough for grilled polenta rounds, crostini of rye, or buttered lavash for varied textures and flavor pairings. ## Notes This recipe turns humble king oyster mushrooms into upscale 'scallops' with deep caramelization and a bright, nutty butter sauce — perfect for cocktail parties or a special starter. Make the brown butter ahead and finish to order for effortless entertaining. ### Storage and Make-Ahead Store leftover grilled mushrooms and sourdough separately in airtight containers in the refrigerator for up to 2–3 days; the bread will soften if stored together. Keep any extra brown butter with capers in a small jar refrigerated for up to 5 days and gently rewarm over low heat. To re-crisp, warm mushrooms briefly in a hot skillet and toast sourdough in a 400°F oven or toaster oven for a few minutes before assembling. ### Serving Suggestions Serve these as a composed appetizer with lemon wedges and extra capers on the side so guests can brighten bites as they like. Pair with a crisp, citrusy white wine such as Albariño or a dry sparkling wine to cut through the butter; a light, herb-forward salad (fennel, arugula, or frisée) or charred asparagus makes an elegant accompaniment. For a heartier first course, arrange on a bed of herbed risotto or creamy polenta and spoon any extra brown butter over the top. ## Frequently Asked Questions ### Why dust the mushrooms with cornstarch? Cornstarch dries the surface slightly and promotes a crisper, more even browning that mimics the seared crust of scallops without adding breading. ### Can I salt the mushrooms in the marinade? Season lightly before grilling, but avoid heavy salting during the 10–15 minute marinade as salt draws moisture and can prevent proper searing; finish with a pinch if needed after searing. ### Will the brown butter make them soggy? If you finish the mushrooms in the butter only briefly (20–30 seconds) and avoid crowding the pan, they’ll absorb gloss without steaming and losing their crust. ### Can other mushrooms be used? King oysters are best because of their dense, cylindrical stems; large shiitakes or thickly sliced portobellos can work in a pinch but won’t have the same scallop-like texture or appearance. ### How do I get those crosshatch grill marks? Place medallions on the hot grate without moving, press gently for full contact, and rotate each piece 90° halfway through the sear on each side to create a professional-looking crosshatch. ## Related Recipes and Guides - [Grilled Shrimp & Charred Corn Warm Salad](https://www.topshelf.recipes/recipes/grilled-shrimp-charred-corn-warm) - [Smoky Grilled Meringue Skewers](https://www.topshelf.recipes/recipes/smoky-grilled-meringue-skewers) - [Charred Caramel Apple Pretzel Bites](https://www.topshelf.recipes/recipes/charred-caramel-apple-pretzel-bites) - [Coffee‑Chile Rubbed Flank Steak Tacos with Charred Pineapple Salsa](https://www.topshelf.recipes/recipes/coffee-chile-rubbed-flank-steak-tacos-charred-pineapple-salsa) - [Grilled Ras el Hanout Chicken Thighs with Charred Apricot-Chickpea Tagine](https://www.topshelf.recipes/recipes/grilled-ras-el-hanout-chicken-thighs-charred-apricot-chickpea-tagine) - [Cedar-Plank Grilled Swordfish Steaks with Warm Olive-Tomato Tapenade and Charred Fennel-Orange Salad](https://www.topshelf.recipes/recipes/cedar-plank-grilled-swordfish-with-olive-tapenade-and-charred-fennel-orange-salad) - [Labour Day Interactive Grill Stations](https://www.topshelf.recipes/articles/labour-day-interactive-grill-stations-2026) - [Skillet to Coals Labour Day Menu](https://www.topshelf.recipes/articles/cast-iron-to-coals-labour-day) - [Labour Day Grilled Grazing Boards](https://www.topshelf.recipes/articles/labour-day-grilled-grazing-boards-12-menus)