Whisk together the sugar, fish sauce, white wine vinegar and soy sauce until the sugar has dissolved.
Heat the groundnut oil in a large wok over a high heat and stir-fry the pork for 4-5 minutes until half-cooked. Add the prepared sauce to the wok and continue to stir-fry for 2-3 minutes, then add the orange and mix well. Remove from the heat and stir in the mint.
Reheat the noodles if necessary and spoon into serving bowls. Top with the pork and orange and garnish with mint leaves before serving.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.