The tri-tip, which is a sirloin subprimal cut of beef, may be oven roasted in the oven at 425 degrees Fahrenheit for 30 to 35 minutes for medium-rare doneness and 40 to 45 minutes for medium doneness. Since tri-tip cuts have very little fat, roasting in the oven past medium doneness is not a good idea.
When roasting a tri-tip in the oven, it is a good idea to use a meat thermometer to check the internal temperature of the meat. The meat will register a reading of 135 degrees Fahrenheit at about the 30 to 35-minute point. Once the meat reaches this temperature, it should removed from the oven and the roasting pan covered with foil. It should stand for 15 minutes, which should raise the internal temperature of the meat up to 145 degrees.
The same process should be done for medium doneness, save for the longer roasting time of 40-45 minutes or when the internal temperature reads 150 degrees Fahrenheit. The internal temperature for medium doneness should read 160 degrees Fahrenheit after letting it stand for 15 minutes covered in foil.
The tri-tip cut is a lean and tender cut of beef from the bottom sirloin. It got its name from its triangular cut. First introduced in California in the 1950s by Otto Schaefer, it is also called Santa Maria steak and triangle roast.