Herbed Chicken Salad Sandwiches

• 1 tablespoon finely chopped fresh tarragon
• 3 tablespoons canola mayonnaise
• 3 tablespoons 2% plain Greek yogurt
• 1 tablespoon fresh lemon juice
• 1/8 teaspoon kosher salt
• 2 cups chopped skinless, boneless rotisserie chicken breast
• 1/4 cup minced sweet onion
• 8 (1 1/2-ounce) slices rye sandwich bread
• 4 red leaf lettuce leaves

Combine the first 5 ingredients in a large bowl. Stir in chicken and onion. Top each of 4 bread slices with 1 lettuce leaf, about 1/2 packed cup chicken salad, and 1 bread slice.