Sous vide is the perfect way to prepare the top round roast cut, also known as London Broil. You can cook it longer than other methods, allowing the exposure to heat to tenderize the meat, while keeping it medium-rare.
Add to the preheated water bath and cook for 8-12 hours. I recommend securing with sous vide magnets to prevent the bag from floating and covering the container with a lid or plastic wrap or foil to prevent evaporation.
Once done cooking in the sous vide bath, remove the bag from the bath and the roast from the bag. Pat the roast completely dry with paper towels or a clean dish towel.