Place onion, carrots and celery in a large pot. Sauté the vegetables over a medium heat until they have softened and browned adequately. Add the potatoes and pumpkin to the pot,  cover it with its lid and simmer until the pumpkin becomes very tender. Adjust seasoning with all the spices and stir the contents of the pot once. Pour in the stock. Boil the soup over a medium heat, until all ingredients are completely soft. Strain the soup, keeping the liquid and vegetables separate. Puree the vegetables and strain through a fine mesh sieve. Place puree back into the soup and heat. Add the lemon, cream and butter. Stir again and simmer for a few more minutes until the soup sets a bit. Serve with a tablespoon per bowl of olive paste, 1-2 apple peelings and one tablespoon of crumbled feta.