All natural, nonfat Greek strained yogurt is the closest substitute to mayonnaise and/or sour cream I've found for many of my recipes, and it works beautifully in this chicken salad. I like the Cayenne pepper for a little kick.
Tweak your yogurt/mayo ratio if you want to go lighter or heavier with the fat.
Lightened Up Chicken Salad
1 ½ pounds chopped, cooked chicken
½ cup finely chopped celery
¼ cup finely chopped red bell pepper
¼ cup finely chopped yellow or green bell pepper
¼ cup finely chopped red onion
1 cup all natural, nonfat Greek strained yogurt
½ cup mayonnaise
1 teaspoon ground red pepper
½ teaspoon kosher salt
¼ teaspoon black pepper
¼ teaspoon Cayenne pepper
Chicken stock
Combine all ingredients in a large bowl and stir. If chicken salad needs a little thinning, add chicken stock for desired consistency.