Poach chicken or purchase 2 cups cooked chicken.
To poach the chicken, bring chicken stock to a boil, turn heat down so the stock is just barely simmering. Roughly chop the celery, carrot and onion and add to the stock along with the chicken, season with a little sea salt and fresh ground pepper, and simmer for 20 min. to ½ hour or until chicken is cooked through but not dry. Remove the skin from the chicken and pull the meat from the bone, discard skin and bone. Shred or chop the chicken into pieces and strain the stock through cheesecloth and reserve.
For the soup:
Cut celery, carrots and onion into bite sized pieces. Heat a Dutch oven or lg. saucepan over medium high heat, add just enough olive oil to lightly coat the bottom of the pan, add the vegetables and sprinkle with sea salt and fresh ground pepper and sauté until lightly translucent and soft. Add enough chicken stock to the reserved stock to measure 6 – 8 cups and add to the vegetables. Add remaining ingredients except the lemon juice and simmer until the spinach is barely wilted, adjust seasonings and serve with a little squeeze of lemon juice.