Coat tofu with potato starch, salt, and pepper.
Air fry at 180C for 12-15 minutes.
For the mushroom sauce, heat cooking oil in a pan.
Add minced shiitake mushroom, red bell pepper, garlic, and ginger.
Stir in soy sauce and vegetarian oyster sauce.
Add water and bring to a simmer.
Mix cornstarch with a little water and stir into the sauce until thickened.
Season with black pepper.
Serve tofu topped with mushroom sauce and garnished with green onion.
