Put tomatoes in bowl and crush by hand, set aside. Swish can with about a ⅓ cup water and set aside for deglazing.
Dry pot roast with paper towels, and, if desired, tie with string to hold together while cooking. Set pressure cooker to sauté and heat a glug of olive oil. Season beef roast with kosher salt and brown on both sides. Remove roast to plate, and deglaze pot with the tomato juice and water. Turn off sauté setting.
Put beef roast back into pot, pour tomatoes over roast. Lift up roast to make sure tomatoes and liquid are evenly distributed, season with salt and pepper. Scatter garlic cloves around roast. Seal and set at high pressure for 60 minutes.
Let pressure cooker naturally release for 20 minutes, then manually release any remaining pressure. Remove pot roast to cutting board, slice or shred meat. Skim fat off tomato mixture and add beef back to pot. Serve beef and sauce over orzo, egg noodles or polenta with some garlic cloves, just press them right out of their papery skins.