Skin the cod and cut into chunks. Squeeze juice from limes and use to marinate the cod for 20 minutes. Meanwhile, fry onion, garlic and spring onions in half of the oil until tender. Add tomatoes and tomato paste. Simmer for 5 minutes stirring occasionally. Add wine and bring to the boil. Season. Strain marinade and dry cod with kitchen paper. Coat cod with flour and gently fry in remaining oil until golden brown, but not cooked through. Put cod in a casserole and pour over sauce. Cover and bake in oven at 200?C/400F/gas mark 6 for 10 minutes. Serve with rice.