Shio Koji-Cured King Oyster Steaks with Aji Amarillo-Miso Purée & Hibiscus Black Garlic Glaze

Instructions

1. 1

   Using the tip of a sharp paring knife, score a diamond crosshatch pattern about 1/8-inch deep into both cut surfaces of 1.25 lbs king oyster mushrooms. In a shallow dish, whisk together 3 tbsp shio koji, 1 tsp ground pasilla chile, and 0.5 tsp fine sea salt. Rub the mixture thoroughly over all sides of the scored mushroom medallions. Arrange in a single layer on a plate and let cure at room temperature for 25 minutes.

   8 min

   Tip: Scoring allows the koji enzymes and chile to penetrate deep into the mushroom matrix, while letting internal moisture weep out during the cure.

2. 2

   Place 1 lb Japanese sweet potato chunks into a medium saucepan, cover with cold salted water by 1 inch, and bring to a boil over medium-high heat. Simmer until the sweet potatoes are completely fork-tender, about 14 to 15 minutes, then drain thoroughly.

   17 min

   Tip: Start from cold water so the sweet potatoes cook evenly from core to edge without waterlogging.

3. 3

   While the potatoes simmer, combine 0.25 cup dried hibiscus flowers, 0.25 cup mirin, 3 tbsp tamari, mashed 4 black garlic cloves, 1 tbsp raw honey, and 0.25 cup water in a small saucepan. Bring to a gentle boil, then lower heat to medium-low and simmer until the liquid is syrupy and coats the back of a spoon, about 8 to 10 minutes. Strain through a fine-mesh sieve, discarding the hibiscus solids, and keep the reduction warm.

   10 min

   Tip: The hibiscus provides malic and citric acidity that cuts through the earthy richness of the black garlic and miso.

4. 4

   Transfer the drained, hot sweet potatoes to a blender or food processor. Add 2 tbsp aji amarillo paste, 2.5 tbsp shiro miso, 2 tbsp unsalted butter, and 0.5 cup kombu dashi. Purée on high speed until completely smooth, glossy, and satin-textured, adding an extra splash of dashi if needed. Season with a tiny pinch of salt to taste and keep warm over low heat.

   6 min

   Tip: Emulsifying hot potato starch with fat and miso creates a luscious texture without needing heavy cream.

5. 5

   Take the cured mushrooms and gently scrape off the excess shio koji solids using your fingers or a paper towel, then pat both cut sides thoroughly dry with clean paper towels.

   3 min

   Tip: Surface moisture and excess rice bits from koji will steam the mushroom or burn prematurely in the pan. Get them as dry as possible.

6. 6

   Heat 2 tbsp grapeseed oil in a large heavy cast-iron skillet over medium-high heat until shimmering. Add the cured mushroom medallions cut-side down, leaving space between each piece. Sear undisturbed for 4 minutes until deeply caramelized and bronze. Flip the steaks, then add remaining 2 tbsp unsalted butter, crushed 2 cloves garlic, and 3 sprigs fresh thyme to the skillet. As the butter foams, tilt the pan and baste the mushrooms continuously with the hot aromatic fat for 3 minutes until tender throughout.

   8 min

   Tip: Treat these exactly like filet mignon. The scored pattern will puff open and catch the browned butter and thyme oils.

7. 7

   To serve, spread a generous swoop of the warm aji amarillo-miso purée across four warmed dinner plates. Arrange 2 to 3 seared king oyster steaks over the purée. Drizzle the warm hibiscus-black garlic glaze around and over the mushrooms. Finish with a sprinkle of 1 tsp toasted white sesame seeds and the curled 2 stalks scallions.

   5 min

   Tip: Plate immediately while the mushrooms are sizzling and the sweet potato silk retains its sheen.