1. Place chicken in a medium sauce-pan and cover completely with cold water. Bring to a simmer over high heat; reduce heat to medium low and cook, turning occasionally, until no longer pink in the center, 15 to 18 minutes. Remove chicken from poaching liquid, let cool and shred.
2. In a large bowl, whisk together canola oil, soy sauce, maple syrup, vinegar, sesame oil and ginger. Stir in chicken and refrigerate, covered, until cold, 40 minutes to 1 hour.
3. Stir snow peas, carrots, scallions, radishes, cashews and herbs into chicken mixture. Divide chicken salad among lettuce leaves.