If using palm sugar, crush it first in a mortar and pestle (it may help to microwave it a bit or moisten it first). Combine the sugar, lime juice, ginger, salt, and sesame oil in a small container with a lid. Shake well to dissolve the sugar. Taste and adjust the balance of flavors. The dressing should be fairly sweet.

Just before serving, combine the dressing with the mango, red onion, green chile, most of the sesame seeds, and most of the herbs. Toss well to coat with the dressing.

Garnish with the remaining sesame seeds and herbs, and serve.