Make sure the 16 ounces of baby bella mushrooms are cleaned and completely dry (wipe with a damp cloth or soft brush, then dry thoroughly).
If any mushrooms are particularly large, cut them into halves or quarters so pieces are similar in size for even cooking.
In a mixing bowl, add the mushrooms and the following: 2 tablespoons extra-virgin olive oil, 1/2 teaspoon garlic powder, 1/4 teaspoon onion powder, 1 tablespoon soy sauce, and 1/2 teaspoon sea salt. Toss until the mushrooms are evenly coated.
Preheat the air fryer to 400°F.
Arrange the coated mushrooms in a single layer in the air fryer basket, avoiding overcrowding. Cook at 400°F for 10 to 15 minutes.
Halfway through cooking (about 5–7 minutes), shake the basket or use tongs to turn the mushrooms so they brown evenly.
Check for doneness at 10 minutes; the mushrooms are done when they are tender inside and crisp at the edges. Remove from the air fryer and serve.