Steam the potatoes, then peel and cut into quarters lengthways. Heat the butter in a wide pan and add the sugar, ginger, chilli powder and seasoning. Allow to cook for a few moments and then add the potatoes, making sure that they are well coated with the spices. Continue to cook on a high heat, stirring all the time, until the potatoes are caramelised. Remove from the pan and keep warm.
Add the carrots and the green pepper and fry for 5 minutes. Add the orange juice and the vinegar and cook until the liquid is reduced by half. Return the potatoes to the pan and stir gently until evenly mixed.