Please note that these instructions are based on using an Instant Pot Air Fryer Lid, and that other air fryers may vary in technique, time and temperature.
Microwave your steam bag of Brussels sprouts until done, usually about 4 minutes. Allow them to rest for a few minutes before opening to prevent steam burns. Pour them out onto a baking sheet or plate.
Using a fork, smash them down until about 1/4" thick. This should be very easy to do. They will release some water, and that is totally fine.
Drizzle with about 1 tsp of olive oil or sunflower oil, and mix to coat. Season with salt, pepper and garlic powder on both sides, and place in the air fryer bucket, being careful not to overcrowd.
Place the broiler lid over (see pictures), then place the lid on top. Set the temperature to 400 degrees, and the timer to 10 minutes. Once 10 minutes is up, carefully remove the lid and broiler lid, and flip the Brussels sprouts. Note that they will be hot! Cook for another 10 minutes at 400 degrees. Enjoy!