Remove the skin and bones from the cooked chicken and cut the meat into bite-sized pieces.
Dice the cooked potatoes and carrots.
Peel and dice the apples.
Chop two of the hard-boiled eggs and reserve the third for garnish.
Toss the apples with the lemon juice to prevent browning.
In a large bowl, combine the chicken, potatoes, carrots, apples, and chopped eggs.
In a separate bowl, whisk together the mayonnaise, sour cream, lemon juice, sugar, and salt until smooth.
Pour the dressing over the salad and gently toss until evenly coated.
Arrange lettuce leaves on a serving platter and spoon the salad into a mound.
Garnish with slices of the remaining hard-boiled egg and chopped fresh herbs.
Chill for at least 30 minutes before serving.