HEAT THE OIL IN A SOUP POT over medium heat and add the chicken, onions, celery, carrots and curry. Cook 15 minutes. Add the water, cider, salt, pepper and lentils. Cover and simmer for 30 minutes. Add the potatoes and dill, replace cover and cook until potatoes are tender, another 10 minutes. Remove from heat, add the apples, stir in the yogurt and pour into a soup tureen. Garnish with sprigs of cilantro and serve immediately.