Fill a large, shallow pan with water. Bring to a boil and add 1/2 teaspoon salt. Add chicken. Simmer, covered, until just cooked through, about 12 minutes. Drain and set aside to cool. Cut into 1/4-inch dice and refrigerate until cold.
Combine mayonnaise, yogurt, onion, lime juice, curry powder, honey, ginger, pepper and remaining half-teaspoon salt in a large bowl. Add chilled chicken and stir to combine. Fold in grapes and mango and serve immediately.
If making in advance, combine chicken with sauce and refrigerate. Fold in grapes and mango a half-hour before serving.
Serve over lettuce, as a filling for sandwiches, as a spread for crackers or just by itself. Enjoy!