In a large bowl, toss brussel sprouts with oil, salt, and pepper.
Set oven, air fryer, or instant pot to 375 degrees/saute, more. Air fry for 8 minutes / roast or saute for 14 minutes.
Open lid/door, stir, and sprinkle on romano cheese; cook for another 6 minutes or until very crispy and cheese is just brown. Once cooked, remove into large bowl and toss with the fish sauce.