Fill a saucepan with water and bring to a boil. Place tomatoes in boiling water and cook for 3 to 5 minutes, or until skins begin to crack and peel. Remove from water, cool and peel.
Puree tomatoes with ginger and garlic in a food processor or blender.
Place tomato mixture, sugar, vinegar, onions, and sultanas in a large saucepan. Season with mixed spice, chilli powder, paprika and curry paste. Simmer over medium heat until thick. Refrigerate until ready to use.