For
Vitamix: Start on Variable Speed 1, turn the machine on and slowly increase to speed 10/High. Use the tamper to press the frozen ingredients into the blades, process until the material is thoroughly incorporated. When the sound of the motor changes, and you have four mounds at the top of the sorbet, you are done. This should take 30 seconds to one minute, depending on how hard-frozen your grapefruit is.