Tri-tip roast is best when cooked by dry-heat methods, such as roasting, grilling, or broiling. This lean cut becomes tough if overcooked. To ensure a juicy result, leave the fat on so it can baste and tenderize the meat while cooking, then trim it off before serving.
To achieve the doneness you want, use a meat thermometer and cook to 5 to 10 degrees below the desired temperature. Temperatures for medium rare are 145F (63C), for medium 160F (71C), and for well done 170F (77C). Remove roast from the oven or grill and let stand 10 to 15 minutes. The roast will continue cooking as it stands.
Tri-tip roast may be marinated or rubbed with a spice mixture before cooking. The purpose of rubs or marinades is not to tenderize this already tender cut, but to add flavoring.
To roast, place tri-tip steak in an ovenproof pan and cook in a preheated oven at 450F (220C) for 30 to 45 minutes, depending on desired degree of doneness. Carve the roast against the grain.
To broil, place tri-tip roast 4 to 5 inches (10-12cm) from the heat sources and broil 25 to 30 minutes, depending on desired degree of doneness. Carve the roast against the grain.
To grill, oil the tri-tip roast, or rub it with a seasoning mixture if desired, and place it over medium heat for 30 to 35 minutes, depending on desired degree of doneness. Carve the roast against the grain.