Chicken Salad with Grapes and Walnuts

• 1 1/2 pounds chicken tenders
• 5 cups water plus 1 3/4 cups reduced-sodium chicken broth
• 1/3 cup plain yogurt
• 1/3 cup mayonnaise
• 1 Tbsp Dijon mustard
• 1 cup seedless grapes, halved crosswise
• 1 cup coarsely chopped walnuts (3 ounces)
• 1 cup celery chopped
• 3 Tbsp drained capers, chopped

Toss chicken with 2 tsp salt. Bring water and broth to a boil in a large saucepan, then add chicken and cook at a bare simmer, uncovered, stirring occasionally, until just cooked through, about 5 minutes. Drain and cool, then tear into 1-inch chunks.

Meanwhile, stir together yogurt, mayonnaise, and mustard.

Stir chicken and remaining ingredients into dressing with salt and pepper to taste.