On one end of the roast, slide the blade of your knife between the meat and the shiny connective tissue.
Immediately begin to pull the connective tissue back away from the meat as you continue to cut between the two until you've reached the other side of the roast. Work in strips if necessary and repeat as needed.
To tie the beef:
Using 12-inch lengths of kitchen twine, tie a loose knot around one end of the meat and pull until snug to make an anchor knot.
Pull a length of twine away from the anchor to create a large loop, then loop it around the tenderloin, spacing it about 1 1/2 inches from the anchor knot.
Pull more twine to create another loop and secure it 1 1/2 inches from the second loop.
Continue tying the roast crosswise at 1 1/2-inch intervals until the toast is evenly tied.
Kitchen twine: My top pick is any butcher’s twine made from cotton. Linen twine is a close runner-up, and if you don't have access to either of those, unflavored dental floss can work in a pinch.
Beef tenderloin: My Roast Beef Tenderloin recipe calls for a 2-pound portion, but feel free to use this method for how to tie beef tenderloin with whatever meat serving matches your crowd size. Look for center-cut beef tenderloin, also known as Châteaubriand, which has a thick layer of fat that needs to be removed before roasting.