Trim the tenderloin of excess fat and silver skin
Tuck the thin tail end under the roast to create a more even shape
Cut kitchen twine into several long pieces
Place the first piece of twine under the tenderloin and center it
Bring both ends of the twine up over the top and tie a snug knot
Repeat the ties every 1 to 1.5 inches along the length of the roast
Keep each tie firm enough to hold shape but not so tight that it cuts into the meat
Trim off any excess twine ends
Check that the tenderloin is evenly shaped and secured before cooking