Curried Chicken Salad

INGREDIENTS

• 1 cup walnut halves
• 4 cups diced cooked chicken (about 12 oz.)
• 1 cup seedless red grapes, halved crosswise
• 1 large celery rib, halved lengthwise and thinly sliced crosswise
• 2 scallions, trimmed and thinly slice
• 1/2 cup mayonnaise
• 1/3 cup plain low-fat yogurt or sour cream
• 1 tablespoon distilled white vinegar
• 1/4 teaspoon curry powder
• 1/4 teaspoon pepper
• 6 radicchio cups
• 4 cups mixed baby greens (about 3 oz.)