Clean and pat the shanks dry. Season both sides with salt and pepper. Set cooker to saute-high. Add olive oil. Place the beef shanks in the cooker. Cook/sear both sides for 3-5 minutes per-side or until brown. Remove the shanks and set aside.
Add onions, carrots, celery and cook for 2-3 minutes or until onions become translucent. Add garlic, sauté ~30 seconds or until fragrant. Pour red wine in the cooker and deglaze the bottom of the cooker for 2 minutes.
Add the beef broth - stir/mix. Return the beef shanks to the cooker. Place crushed tomatoes on top of the beef shanks. Do not stir.
Place the lid on. Pressure cook on high for 40 minutes, followed by a natural release. Follow the manufacture instructions for releasing the pressure. Remove the lid.
Gently scrap the crushed tomatoes off the beef. Carefully remove the beef shank from the cooker and set aside. Scoop out and discard grease. Set cooker back to saute-high. Sauté until the liquid reduces to about half. Season with salt and pepper to taste. Press cancel.