You can use this method of cooking fish for mackerel, plaice and also the thicker fishes like haddock or ling just cook them longer. When using pesto coat the fish in pesto first then cook. This sauce is great with Fish, Lamb Chops, Chicken, Pasta You could add in half a finely chopped red chilli when cooking the onion and replace the basil with coriander and you have a spicy tomato sauce Alternatively in a roasting dish put 1 roughly chopped aubergine, red pepper, courgette and then pour over the tomato and basil sauce and place in an oven at 180C for 40 minutes and this make ratatouille.