Whisk together the sugar, lime juice, ginger and fish sauce in a mixing bowl until the sugar has dissolved. Add the sesame oil, whisk well and add the fish, allowing it to marinade for at least 15 minutes.
Preheat the grill to hot.
Remove the fish from the marinade and place on a lined baking sheet. Grill for 6-8 minutes, turning occasionally, until lightly coloured and cooked through. Towards the end of grilling, add the dill and pepper to warm through.
Arrange the rice noodles on serving plates and top with the pepper, peanuts, dill and chunks of fish. Serve immediately.