Heat the vegetable oil in a large pan. Sprinkle the potatoes with salt and very gently simmer in the oil for 15 minutes until tender but not coloured. Drain and reserve the oil.
Heat the olive oil in a pan and gently fry the onion and peppers or capsicums over a low heat for 10 minutes until soft and sweet. Add the garlic and cook for 5 minutes more. Add the tomato passata, sugar, papri