Trim pork of any large pieces of fat.
In the bowl of a mini-food processor or a blender jar, combine the garlic, lemon juice and zest, majoram, rosemary, soy sauce, salt, pepper, and red pepper flakes.
Pulse until the garlic and herbs are finely chopped. Slowly drizzle in the olive oil while the machine is running until a loose paste forms.
Rub the garlic paste over both tenderloins, covering all surface
Cover the pork tightly with plastic wrap and refrigerate for 2-8 hours before grilling
When ready to cook, start the Traeger grill on Smoke with the lid open until the fire is established (4 to 5 minutes). Set the temperature to 400F and preheat, lid closed, for 10 to 15 minutes or preheat grill or oven to 400 degrees
Arrange the tenderloins directly on the grill grate at an angle to the bars. Roast for 15 minutes.
Using tongs, turn the tenderloins and continue to roast until the internal temperature in the thickest part of the meat registers at least 145F. At that temperature, the pork will be slightly pink inside. If you prefer your pork more well done, roast it until it reaches 160F.
Let the meat rest for 5 minutes before carving into slices. Shingle the slices attractively on a platter, garnish with the lemon slices and remaining herb sprigs, and serve.