Sprinkle chicken with pepper and salt. Pour broth into a large skillet; bring to boiling. Add chicken; reduce heat. Simmer, covered, for 12 to 14 minutes or until chicken is no longer pink (170 degrees F), turning once. Using a slotted spoon, remove chicken from broth; discard broth. Meanwhile, prepare the Warm Citrus Dressing.
Thinly slice chicken. In a large salad bowl combine chicken, spinach and/or watercress, and strawberries.
Drizzle the warm dressing over spinach mixture; sprinkle with nuts. Serve immediately.
Warm Citrus Dressing
In a blender or food processor combine strawberries, orange juice, canola oil, lemon peel, lemon juice, sugar, chili powder (if using), freshly ground black pepper, and salt. Cover; blend or process until smooth. Transfer mixture to a small saucepan; bring just to boiling. Simmer, uncovered, for 5 minutes, stirring occasionally. Keep warm until needed. Makes 3/4 cup dressing.