Season the beef briskets with salt and black pepper.
Put the butter and minced garlic in the Instant Pot and select “Sauté”.
Sauté for 45 seconds and add onions and green chilies.
Sauté for 3 minutes and add tomatoes and seasoned beef briskets.
Set the Instant Pot to “Manual” mode for 14 minutes at high pressure.
Release the pressure naturally and slice into desired slices.