In deep, 2-quart saucepan, place chicken, celery and cold water. Chop 1 quarter of the onion very fine and set aside; add remaining 3 quarters of onion and 1 teaspoon of the salt to saucepan. Over high heat, bring to a boil; reduce heat to low, cover and simmer until chicken is tender, about 15 minutes. Cool chicken and separate meat from bones, discarding bones and skin. Cut chicken into thin strips. In large bowl, place chicken, potatoes, dill pickle and reserved chopped onion; sprinkle with remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Mix together mayonnaise, sour cream and Worcestershire sauce; gently add to chicken mixture. Cover and chill in refrigerator until serving time. Garnish with boiled egg quarters, olives and tomato wedges.