To poach chicken breast, add a few thin slices of ginger in a pot of water. Bring to boil. Add the chicken, reduce the heat to low and simmer for 5 minutes. Remove the pot from heat, and leave chicken breast to stand with lid on for 20 minutes or longer. Shred the chicken breast; set aside.
To make the fish sauce dressing, Put palm sugar (or brown sugar) in a small mixing bowl. Add boiling water to dissolve the sugar. Add the garlic, chili, fish sauce, vinegar, and lime juice, and stir well.
To assemble the salad, combine shredded chicken, salad vegetables, and herbs in a large mixing bowl. Pour about 1/3 cup of dressing to the salad and toss well. Add more dressing to get your preferred taste.
Garnish salad with chopped peanuts and crisp-fried shallots (if using) and serve immediately.