If using chicken, cube and place into a large stockpot then rinse once with water and discard the rinse water, after rinsing cover with the 15 cups of water and bring to a boil then turn heat to low and allow to simmer gently while preparing vegetables. If using beef, do not rinse. If using the same knife and chopping board as the chicken or beef, wash well before using again. Peel and wash the onion, parsnip, sweede, carrots and wash the celery, then place on a plate ready for them to be diced in the order given above, adding to the stockpot as you dice them. Stir soup after each addition of an ingredient. When the above vegetables have been added, leave to simmer for at least an hour before adding any of the following ingredients ( If you add the other ingredients too soon it will turn to mush and not soup. ) If using soup mix, pearl barley, lentils, large pasta or rice these can now be added and simmer for 20 minutes more, while you peel and wash and dice the pumpkin, then wash the cauliflower and broccoli and cut into sections and add to the soup, after the extra 20 minutes of simmering and continue to simmer for 5 minutes more, if using peas or 2 minute noodles then they can be added also. Turn heat off and leave on the stovetop until ready to serve. I dont add the salt, pepper or parsley until at the table as everyone has thier own tastes but they can be added at the very last if desired.