Ground black pepper. pn Salt. Heat the oil in a pan and gently fry the onions for 8 minutes. Add the garlic and fry for a further 2 minutes. Mix all the ingredients together in a bowl. Place the mixture in a large greased oven proof dish and cover with foil. Cook in the oven at 180 c, 350 f, gas mark 4 for 1 and three quarter hours.