Place 1/2 cup water and onion into the Vitamix container and secure lid.
Select Variable 1.Turn machine on and slowly increase speed to Variable 10, then to High.
Blend for 10 seconds.
Pour onion mixture into a large pot. Add 4 cups of water, chopped onion, chopped broccoli, sliced carrots, chopped celery and all the wonderful seasonings and bring to a boil. Then cover and simmer for 15 minutes.
Next, remove 2 cups of the soup and carefully place into the Vitamix container and secure lid. Set the Vitamix to pre-programmed Hot Soup setting and start the machine. It will automatically shut off once the cycle is complete.
Pour blended soup back into pot (add optional: cheddar cheese) and stir. Simmer for 10 minutes more.