In a large sauce pot, combine carrots, onion, celery, sweet potato and chicken stock. Cook until the vegetables are tender. DO NOT DRAIN. Cool vegetables for a short time. Place vegetables and their juices in a food processor. Process vegetables until they are blended and smooth. If mixture is too thick, add a cup of water until it is thick but not diluted. Place blended mixture back into a medium to large pot and bring to a slow simmer. Add the orange juice, thyme, curry powder, sea salt and pepper. Simmer for 20 to 30 minutes. Remove from heat and cool. Once soup has cooled, place in airtight containers and freeze. This soup serves 8 to 10. Soup can be made a week or two in advance and frozen. Partially thaw and heat through when ready to serve. Delicious with a spoon of sour cream or low fat Greek yogurt served on top. Serve a bowl with a whole grain roll and a tossed salad.