Prepare the mushrooms: use a damp cloth or paper towel to wipe them clean. Remove the stem by gently twisting it off.
Preheat your air fryer to 375 degrees F
Mix the balsamic vinegar, oil and spices together in a small bowl.
Use a pastry brush to spread the oil and balsamic mixture onto the mushroom caps.
Arrange the mushroom caps on a air fryer basket with the gill side facing down leaving enough room so that the air can circulate around them.
Place the basket or tray into a preheated air fryer and air fry for 8 minutes. Flip the mushrooms over and air fry until the mushrooms are deep brown about 2 to 5 minutes longer.
Notes
Serve as a burger on your favorite bread, as a side or tossed into a salad.Store leftover portobello in the refrigerator for 3 days.See article above for variations, tips and more.