Roast beef is a classic dish with a variety of applications. No surprise, sous vide is the most foolproof method to keeping the meat juicy and flavorful. Low and slow cooking while constantly bathing the meat in its own juices create a winning combination for a variety of cuts.
3lb.beef cut hunk (e.g. chuck, eye of round, tri-tip)
Set the sous vide cooker at 54.4°C / 130°F to preheat the water. This is the right temperature for beef to get that perfect pink center.
Place the beef in the vacuum seal bag. Add the rosemary, garlic cloves and olive oil before sealing the bag.
When the water reaches temperature, place the bag into the sous vide container. Cook for 21 hours +/-3.
Once the beef has finished cooking, take it out of the vacuum sealed bag.
Discard the liquid, and dry the meat down for a good sear.
Pre-heat the cast-iron skillet at medium-high heat for 5+ minutes, melting the butter with about a minute left of the pre-heat.
Place the roast beef on the hot skillet, searing in butter for 20-30 seconds per side until all sides are golden brown. If the desired sear hasn't been achieved after the first 30 seconds, repeat a 20-30 second sear AFTER searing the other sides.
Season with salt as desired and it's ready to eat. No need for rest. Cut against the grain.
If thin cuts are desired for something like sandwiches, cooling the meat and a sharp knife will be helpful.