Cuts

Knife Cuts — Regional & Global

Mushroom Planks

Also: mushroom steaks, portobello steaks, king oyster planks, mushroom slabs

Thick vertical slabs cut from large portobello or king oyster mushrooms, designed to withstand direct grilling or searing as a plant-based centerpiece.

A mushroom plank is a broad, flat slab — typically 1–1.5 cm thick — cut vertically through the full cap or stem of a large mushroom, yielding a piece with maximum surface area on two flat faces and a cross-section that exposes the dense interior flesh. The geometry mimics a thin steak or fish fillet, making it suitable for the same direct-heat cooking methods. The plank cut is distinct from a bias or diagonal cut in that it is made perpendicular to the cap's dome or parallel to the stem's length, resulting in uniform thickness and a broad, flat profile.

In photos

Mushroom Planks in its raw whole-cut form on a butcher's board — A mushroom plank is a broad, flat slab — typically 1–1. Identifying traits: Broad, flat faces maximize Maillard browning contact on a grill or skillet, Uniform thickness ensures even cooking through without burning the exterior, Dense flesh holds up to direct flame, grill grates, and weighted presses.
Mushroom Planks in its raw whole-cut form on a butcher's board — A mushroom plank is a broad, flat slab — typically 1–1. Identifying traits: Broad, flat faces maximize Maillard browning contact on a grill or skillet, Uniform thickness ensures even cooking through without burning the exterior, Dense flesh holds up to direct flame, grill grates, and weighted presses.
Where the mushroom planks lives on the source. Most commonly applied to: (1) Portobello mushrooms (Agaricus bisporus, mature) — caps stem-removed and sliced downward through the crown.
Where the mushroom planks lives on the source. Most commonly applied to: (1) Portobello mushrooms (Agaricus bisporus, mature) — caps stem-removed and sliced downward through the crown.
Mushroom Planks prepared the canonical way — Portobello mushroom burger. For portobello: remove stem flush with the cap (reserve stem for stock), wipe cap clean, and slice vertically downward through the crown into 1–1.5 cm slabs. Each large cap yields 2–3 planks.
Mushroom Planks prepared the canonical way — Portobello mushroom burger. For portobello: remove stem flush with the cap (reserve stem for stock), wipe cap clean, and slice vertically downward through the crown into 1–1.5 cm slabs. Each large cap yields 2–3 planks.

Where it comes from

Most commonly applied to: (1) Portobello mushrooms (Agaricus bisporus, mature) — caps stem-removed and sliced downward through the crown; (2) King oyster mushrooms (Pleurotus eryngii) — thick, dense stems sliced vertically into planks while caps may be reserved separately; (3) Lion's mane (Hericium erinaceus) — torn into large slabs that self-plank when pressed flat on a hot surface.

Broad, flat faces maximize Maillard browning contact on a grill or skilletUniform thickness ensures even cooking through without burning the exteriorDense flesh holds up to direct flame, grill grates, and weighted pressesCross-section texture visible on plate — visually communicates 'steak' compositionSponge-like interior absorbs marinades deeply when given enough contact timeStructurally intact enough to be eaten with a fork and knife

Best for

Direct grilling over charcoal or gasCast-iron searing with butter bastingPlancha cookingSmash-cooking under a weighted panPlant-based burgers and sandwiches (portobello plank in a bun)Grain bowl and composed plate centerpieces

How to cook it

  1. 1For portobello: remove stem flush with the cap (reserve stem for stock), wipe cap clean, and slice vertically downward through the crown into 1–1.5 cm slabs. Each large cap yields 2–3 planks.
  2. 2For king oyster: trim the base, stand the mushroom upright, and cut vertically through the stem into 1–1.5 cm planks. Smaller king oysters yield one full plank; large ones give two.
  3. 3Marinate planks 20–30 minutes in oil, soy sauce, balsamic, garlic, and herbs. The broad flat faces allow even coating. Do not marinate longer than 1 hour — acids degrade the texture.
  4. 4Pat planks dry before cooking; surface moisture prevents browning and causes steaming.
  5. 5Grill or sear over high heat (230°C+), pressing planks flat with a spatula for the first 60 seconds to maximize contact. Cook 3–4 minutes per side until deep golden with grill marks.
  6. 6Baste with butter, thyme, and garlic in the final minute if pan-cooking. Rest 2 minutes before plating.

Prep & butchery

  • Cold mushrooms firm up and slice more cleanly; refrigerate 30 minutes before cutting if slipping on the board.
  • A long, thin-bladed slicer or chef's knife minimizes tearing through the cap tissue.
  • For portobello, trim dark, slimy gill edges on the underside with a spoon before slicing if presentation is critical — gills bleed dark liquid onto the plate.
  • Score a shallow crosshatch (2–3 mm deep) on each flat face after slicing to help marinade penetrate and prevent curling during high-heat cooking.

Substitutes

  • Eggplant rounds (1.5 cm)

    Similar shape and grilling behavior; less meaty but absorbs smoke and oil comparably

  • Cauliflower steaks

    Thicker and denser; requires longer cooking but comparable plant-based centerpiece role

  • Whole portobello cap (unsliced)

    Classic burger substitute; less 'steak-like' but simpler to prepare and more familiar

Related cuts

  • Mushroom tear-cut for banchan

    Opposite philosophy: exploits rough, irregular grain surfaces for sauce absorption rather than smooth browning faces

  • Cauliflower steak

    The same slab-from-vegetable concept applied to brassicas; analogous cooking methods

  • Tomato concassé planks

    Thin tomato slabs used for carpaccio-style plating — same flat-face geometry, different purpose

Appears in

Portobello mushroom burgerGrilled mushroom steak with chimichurriKing oyster mushroom scallopsPlant-based steak au poivreMushroom banh miGrain bowls with roasted mushroom planks

References

  1. 1.The Vegetarian Butcher — Joep Zander & Niko Koffeman
  2. 2.Plenty More — Yotam Ottolenghi
  3. 3.The Wicked Healthy Cookbook — Chad Sarno & Derek Sarno
  4. 4.On Vegetables — Jeremy Fox

Confidence: high

Notes

King oyster vs. portobello: structural differences

King oyster stems are dense with tightly packed, longitudinally oriented hyphae — cutting parallel to these fibers produces a plank that holds together under heat and can even be pulled apart in strands post-cooking, mimicking a scallop or pulled pork texture. Portobello caps are radially structured around gills; cutting through the crown produces a plank with visible gill patterning underneath and a softer, more yielding texture than the king oyster — closer to a thick filet of white fish.

The smash technique

A trick borrowed from smash-burger cooking: place the plank on a ripping-hot dry skillet and immediately press with a heavy flat weight (cast-iron press, brick wrapped in foil) for 60–90 seconds. The pressure collapses air pockets and drives the surface into the pan, dramatically accelerating browning. Repeat on the second side. The crust formed this way is more complete and faster than conventional flipping without pressing.