One of the most important points about cooking fish is to leave it be. Too often as cooks one tries to shake the pan, flip whatever we are cooking, feel that we ought to be doing something, but this isn't always the best solution. Things need to be left in the pan, in one place, to develop a nice crust. Start flipping your fish all over the place and it will just fall apart.
The way you cook your fish can depend on what it is – somehow plaice always lends itself to being bread crumbed and fried in butter while mackerel suits the barbecue or a spankingly hot grill.
Grilling can be the simplest method for cooking most fish. Pre-heat the grill as hot as possible before you start; brush thinner fillets with some olive oil or butter before cooking – oily fish like mackerel and sardines are happy as they are.
Deep frying is the classic British method of cooking fish, the batter encasing and protecting the fish against the searing heat of the oil, retaining a lot of moisture. The oil must be at the right temperature, so use a thermometer or a deep fat fryer – this will ensure the batter seals as soon as the fish hits the oil.
Baking, either en papillote (in a paper bag or foil) or just on a baking sheet. En papillote can be fun and simple as you can add other ingredients to the bag – vegetables or herbs, a splash of white wine. All the steam is trapped inside the bag, ensuring the fish stays moist.
Poaching is a gentle cooking method for fish and adding ingredients to the poaching liquor can add different flavours to the fish – vermouth, lemon or orange zest, star anise, fennel seeds...the world is your oyster. Well, fish.
Pan-frying is the most common restaurant method of cooking fish – quick and easy. Use a mixture of butter and oil. You can dip the fish in a little flour to ensure a crisp coating before frying, tapping off the excess. A nice method of cooking fish is to sear it on one side in a hot pan, watch the edge of the fish and the colour moving up through it – as soon as it gets half-way, turn it over and turn the heat out from under the pan and leave for a few minutes to finish.
Steaming is a great way to keep fish moist while imparting flavour. Place fresh herbs, lemon slices or pieces of ginger in your steamer before placing the fish on top.
Last but not least, the microwave can be a useful tool for cooking fish if you aren't comfortable with the other methods. As power settings vary, you'd need to refer to the cooking guidelines for your microwave – but you can still add a herb butter or citrus to your fish before it cooks.