Prep the mushrooms. Gently brush off dirt with a dry towel.
If there are tougher stem ends, trim them. Tear the mushroom into 1- to 2-inch chunks. Tearing creates more craggy edges that crisp better than slicing.
Dry them well. Pat the pieces with paper towels to remove surface moisture.
Drier mushrooms brown more easily and won’t steam in the air fryer.
Mix the seasoning. In a large bowl, whisk the olive oil, soy sauce, Dijon, smoked paprika, garlic powder, onion powder, black pepper, and a small pinch of salt.
Toss to coat. Add the mushroom pieces and toss until every surface is glossy. Let them sit for 5 minutes to absorb flavor while you preheat.
Preheat the air fryer. Set it to 380°F (193°C) for 4 to 5 minutes. Lightly spray the basket if sticking is a concern.
Arrange in a single layer. Spread the mushrooms in the basket without crowding.
If needed, cook in two batches for even browning.
Air fry. Cook at 380°F (193°C) for 8 to 12 minutes, shaking the basket halfway. The mushrooms are done when the tips are golden-brown and the centers feel tender but not spongy.
Taste and finish. Sprinkle a bit of salt if needed. Squeeze lemon over the top and add chopped parsley or your favorite finishing sauce.
Serve hot. They’re best right away, next to roasted veggies, on polenta, folded into tacos, or on a toasted bun like a crab-less cake.