For the sauce
To make the sauce, heat the oil in a pan. Add the onion, then cook until soft but not coloured. Add the garlic and cook for another minute. Add the spices and cook for 1 min.
Add the tomato puree and mustard powder and cook for 1 min until the puree turns a deep, dark red. Add the remaining ingredients, season with salt and black pepper, then stir and bring to the boil. Lower the heat and let it simmer for 10 min. Puree with a stick blender until smooth. Leave to cool.
If they are not precooked, you will need to poach them first in simmering water, then fry or grill until they are crispy and form a brown crust. Cut into bite-size chunks, top with the curry sauce and serve with fries on the side. They are traditionally served in paper trays and eaten with cocktail sticks
