1. Prepare the “Buttermilk” and Slaw:

2. In a medium bowl, combine the 1 cup of plant-based milk and 1 tablespoon of apple cider vinegar. Stir and set aside for 5-10 minutes to curdle slightly. This will act as your vegan buttermilk. While it rests, prepare the slaw. In a separate bowl, whisk together the vegan mayonnaise, apple cider vinegar, maple syrup, celery salt, and black pepper until smooth. Add the shredded cabbage mix and toss until everything is well-coated. Cover and refrigerate until you’re ready to assemble the sandwiches. This allows the flavors to meld.

3. Prepare the Mushrooms:

4. Clean the king oyster mushrooms by wiping them with a damp paper towel. Avoid washing them under water as they can become waterlogged. Trim off the very bottom of the stems. Using a sharp knife, slice the mushrooms lengthwise into thick planks, about 1/2 to 3/4 inch thick. You should get 2-3 planks per mushroom. This thickness is key to achieving that “meaty” texture.

5. Set Up Your Dredging Station:

6. You’ll need two shallow dishes. In the first dish, whisk together the all-purpose flour, cornstarch, smoked paprika, garlic powder, onion powder, salt, black pepper, and cayenne pepper. This is your dry mixture. In the second dish, pour your prepared vegan “buttermilk”. This is your wet mixture. A systematic setup (dry-wet-dry) makes the process much smoother.

7. Coat the Mushrooms:

8. Take one mushroom plank and dredge it thoroughly in the dry flour mixture, making sure it’s completely coated on all sides. Shake off any excess. Next, dip the flour-coated mushroom into the wet buttermilk mixture, ensuring it’s fully submerged. Let any excess drip off for a moment. Finally, return the mushroom to the dry mixture for a second, heavy coating. Press the flour mixture onto the mushroom firmly to create a thick, shaggy crust. This double-dredge is crucial for an ultra-crispy result. Place the coated mushroom on a wire rack and repeat with the remaining planks.

9. Heat the Frying Oil:

10. Pour the neutral oil into a large, heavy-bottomed pot or Dutch oven until it’s about 2 inches deep. Heat the oil over medium-high heat until it reaches 350°F (175°C). Using a thermometer is highly recommended for perfect results. If you don’t have one, you can test the oil by dropping a small bit of batter in; it should sizzle immediately and turn golden brown in about 30-60 seconds.

11. Fry the Mushrooms:

12. Carefully place 2-3 coated mushroom planks into the hot oil, being careful not to overcrowd the pot. Overcrowding will lower the oil temperature and result in greasy, soggy mushrooms. Fry for 3-4 minutes per side, until they are a deep golden brown and wonderfully crispy. Use tongs to carefully flip them. Once cooked, transfer the fried mushrooms to a clean wire rack to drain. Do not place them on paper towels, as this can steam the bottom and make them lose their crispiness.

13. Make the Hot Maple Glaze:

14. While the mushrooms are frying or draining, prepare the glaze. In a small saucepan over medium-low heat, combine the maple syrup, hot sauce, melted plant-based butter, soy sauce, and smoked paprika. Whisk continuously and bring the mixture to a gentle simmer. Let it bubble for 1-2 minutes until it has thickened slightly. Remove from the heat.

15. Glaze and Assemble:

16. Once all the mushrooms are fried, it’s time to bring it all together. You can either dip each fried mushroom into the warm glaze or use a pastry brush to generously paint the glaze onto all sides of the crispy mushrooms. Work quickly so the sandwich is served hot. Lightly toast your buns. Spread a thin layer of vegan mayonnaise on the bottom bun, if desired. Place a hot, glazed mushroom plank on top. Add a generous pile of the tangy slaw and finish with a few dill pickle slices. Place the top bun on and serve immediately.