Some vegetables such as yams, sweet potato, potato, beans, grains, eggplant, and other root veggies require pre-cooking. Others such as onion are preferred cooked to reduce the pungent flavors. Vegetables like celery, broccoli, carrots, leafy greens, etc. you can add in raw. The Rx does not heat high enough to cook ingredients. It heats them to about 130-150 degrees F.