Freeze the beef for 30 minutes (optional - easier to cut).
Cut the ribeye against the grain into super thin strips and set aside.
Set the Instant Pot to the Saute setting and add the butter.
Cut the bell pepper and onion into 1/4" strips and add to the Instant Pot.
Saute for 2-3 minutes.
Add the beef, onion powder, Worcestershire and stir to combine.
Put the lid on the Instant Pot and set to 8 minutes on "Pressure Cooker" high setting.
Let NPR for 12 minutes before removing the lid.
Add 2 slices of cheese and stir to melt and combine.
Using tongs, take half the mixture and transfer to the hoagie roll. Repeat with the rest of the mixture.
Add salt to taste and top another slice of cheese (optional).