Chicken Salad 
For the dressing:

1 tablespoon granulated sugar
1 teaspoon plain flour
1/2 teaspoon salt
1/4 teaspoon black pepper
3/4 teaspoon mustard
2 1/2 tablespoons white vinegar
3 tablespoons water
1 egg yolk, lightly beaten
2/3 cup mayonnaise

To make the dressing: In a bowl, whisk sugar, flour, salt, pepper and mustard. Set aside. In a small saucepan, bring vinegar and water to boil. Add the boiled mixture to the egg yolk, stirring constantly, until it is warm to the touch. Gradually add the wet mixture to the dry ingredients, whisking constantly to combine.
Reduce heat to low and pour the mixture back into the saucepan. Stirring constantly, heat the mixture until thickened, 2 to 3 minutes. Do not allow it to boil. Remove from heat, transfer to a bowl and cool thoroughly. Mixed boiled dressing with mayonnaise.

For the chicken salad:

4 1/2 cups diced cooked chicken breast (I used my handy little chopper for this.)
2/3 cup diced celery
dressing mixture
1/4 cup sour cream
1 1/2 teaspoons salt
1/2 teaspoon black pepper

To make chicken salad: Combine chicken, celery, dressing and sour cream. Add additional dressing, salt and pepper if necessary.

Hint: Make it the night before so the flavors can blend.