Season the short ribs with salt and pepper. Turn the Instant Pot on to saute and add canola oil. When it reads ‘Hot’ add your short ribs in (in batches) and sear on both sides, about 5 minutes per side. Once the ribs are brown, add the onion, carrots, celery, garlic, rosemary and red pepper flakes to the pot. Cook for about 5 minutes, or until they are beginning to brown.