Combine brown sugar, soy sauce, sesame oil, vegetable oil, and rice vinegar. Shake and mix well and let sit for flavors to mingle. Cook rice noodles- Heat a wok with a few tablespoons of oil. Break off a little bit of the rice noodles and add them to the skillet and fry them (they will puff up so only add a few at a time). As the rice noodles begin to puff up, remove from the wok and drain on paper towels. Note: undercooked noodles will be tough to eat. .
Toss together the ruffled lettuce, cooked chicken, mandarin oranges, green onions and toasted sesame seeds. Chill for 10-15 minutes in the refrigerator. Just before serving add the rice noodles. Serve with dressing.