Low temperature roasting is an ideal method for cooking leaner tender cuts of meat such as beef tenderloin. There are two methods that both work well.
Sear the beef first then place it in the oven to slowly cook through, rest before slicing.
Slowly cook the meat, take it out when it reaches the desired internal temperature and let it rest then sear it just before serving and slice it right away.
When cooking meats in low temperatures you will find meats retain a great deal more color which some people find alarming. Even though the meat is fully cooked to whatever internal temperature you chose it may look too rare, my solution, pop some slices back in the oven at a low temperature 250 degrees in the Combination Convection Steam Mode for a few minutes and the color will quickly dissipate but the meat will still be very tender.
1 - 3-4lb beef tenderloin
1 - teaspoon kosher salt
2 - cloves garlic, minced
1 - tablespoon, finely chopped fresh rosemary
1 - tablespoon olive oil
Freshly ground pepper
Combine the seasoning with the oil and massage into the beef. Ideally do this a couple of hours in advance to allow the beef to take on the flavors.
Heat the oven in the Convection Steam Mode 200 degrees, place the meat on a shallow rimmed baking sheet and cook for approximately 30 - 40 minutes depending on the internal temperature you prefer. Ideally aim for a few degrees lower than the carving temperature because the meat will be going through a high heat sear before serving.
Let the meat rest for at least 15 minutes or up to an hour then sear in a hot pan on the cooktop or in the oven in the Convection Mode 425 degrees.