Preheat pressure cooker by selecting the saute option.
Pour the water into the pot.
Arrange the brussels sprouts onto the steam rack and lower them into the pot.
Press the keep warm/cancel button.
Place the lid on top and close into locked position.
Turn the steam release valve to closed.
Press the manual button and adjust the timer to 2 minutes.
Once the unit has pressure cooked and counted down, carefully release the steam.
Remove the brussels sprouts with the steam rack.
Dump the water out of the pot and replace.
Press the saute button and add the butter, the juice from the lemon and the brussels sprouts.
Saute until browned.
Place the brussels sprouts in a serving dish and garnish with freshly grated Parmesan.