"I like Dover sole. It's always one of my favorites. I like it when I'm in England. I eat it every day almost. I think it's one of my favorite fish."
Wolfgang Puck, chef, restaurateur and actor (1949-)
It recently occurred to me that I don't poach whole fish very often. Certainly that can be explained by the fact that poaching a whole sea bass or sea trout is usually an activity reserved for a special occasion where the results are to be enjoyed amongst many. But that explanation does not extend to the case of a Dover sole, brill, turbot or plaice, something that can serve two, or even just one. I realised that I was restricting my myself simply because I didn't have an oval fish kettle or a suitably-sized oval pan with a lid. Thinking about it more, of course, one obvious solution is to just use a large, flameproof roasting tin and a sheet of foil to achieve the poaching. Another solution, though, is to simply use the oven.
After quite a lot of research I found that a technique of "oven-poaching" was not entirely unaccounted for but didn't seem to be particularly well-promoted. And in general, recipes of the kind were generally for fish fillets but, where not, cooking times seemed somewhat under-precise. So I set about trying to formulate a set of "rules" that could make poaching a whole fish in the oven a simple and reliable way of achieving such a fabulous way of enjoying fresh fish to its full. After all, poaching is a healthy way to eat (no fat is used) and a largely-forgiving way to cook fish. With the exception of halibut (which will always overcook if given half a chance), it is hard to overcook fish through poaching.
Classically, when poaching a whole fish, for example in a fish kettle, the fish is introduced to a cool liquor, usually a court bouillon, which is then brung to the boil, simmered briefly and then left to cool. However, bringing a liquid to the boil in the oven takes far longer than it does on the hob, so timings are not transferable between the two methods. But the constant shared between them is that a liquid composed predominantly of water will only ever reach a temperature at or close to 100°C, irrespective of the temperature of its environment. One benefit of this is that differences between the precise temperatures being registered by one oven and the next become irrelevant provided the temperature is definitely greater than 100°C. So, knowing we have access to a reliable cooking temperature, we are only a couple of steps away from a formula for our oven-poaching method, which is explained in the remainder of this post.
Very often you will be able to buy whole Dover sole with at least the dark side's top skin removed skinned. This method of cooking works fine even if the fish has not been skinned as, once cooked, the dark skin peels or scrapes away easily with a spoon and the pale skin on the underside is perfectly palatable anyway. The head can, of course, be removed prior to cooking, if preferred.
Serving such a delicately-cooked fish demands equally delicate, or perhaps sympathetic accompaniments. From a sauce point of view I would happily eat a poached Dover sole or brill with Caper Butter Sauce, Sauce Américaine or Watercress Sauce for example. But a simple dressing of good olive oil and lemon juice with perhaps some fresh herbs works perfectly well. For vegetable garnishes I don't think you can beat boiled potatoes (Jersey Royals particularly at this time of year) and some wilted or steamed greens - broccoli (especially purple-sprouting broccoli when in season) and green beans or podded broad beans spring to mind.
Incidentally, Delia says, and I quote: "Don't bother with fish kettles, which take up far too much storage space...". I'm sorry, Delia, I cannot agree, and I don't have a lot of storage space.
In order to have a reliable set of cooking times there are a few things we have to ensure we observe for consistency. First, we need to make sure the fish will be submerged. There's a little tip in the post for Court Bouillon on how to work out how much liquid you need, but it's pretty obvious really: measure it out with cold water before we start. Second, the court bouillon should be boiling before it goes into the dish in which the fish will be poached. Third, that dish should be heated to at least 100°C so that the court bouillon does not cool when introduced to the dish. And fourth and finally, the fish should be at room temperature before it goes into the hot poaching liquid so that it also doesn't bring the temperature of the liquid down more than necessary, although some heat loss is unavoidable.
With these points observed the cooking times for Dover sole should reliably be as follows according to the weight of the fish:
300-450g: 10 mins
450-600g: 11 mins
600-750g: 12 mins
An oval dish is ideal for one large fish whereas a rectangular one is better for two or more individual-portion-sized fish. This helps to ensure the minimum amount of liquid required is used.
Oven-Poached Dover Sole
Ingredients (Serves 2)
1 x 750g or 2 x 350g whole Dover sole, skinned or unskinned
Court bouillon or water, approx 1.5 litre for a 750g fish or 1 litre for 2 x 350g fish
Method
Put the dish in which the fish is to be poached in the oven and heat the oven to 180°C. Once the oven is up to temperature leave the dish in it for a further 5-10 minutes to ensure it reaches a temperature in excess of 100°C. Meanwhile bring the court bouillon to the boil in a saucepan and boil the kettle.
Take the dish out of the oven and pour some of the court bouillon into it (the liquid should bubble when it hits the surface of the dish). Put the fish in the liquid and add the remaining court bouillon. If it happens that the fish is/are not fully submerged top up the liquid with water from the kettle. Cover the dish tightly with foil and return to the oven.
Allow to cook for the prescribed amount of time: 10 minutes for two 350g fish or 12 minutes for a single 750g fish. After the allotted time, remove from the oven and leave covered for a few minutes while you finish off any accompaniments.
Using a fish slice and a large spoon, lift the fish out of the court bouillon and and serve.
Links
"How to Poach and Steam Fish", deliaonline.com, accessed 19 May 2020
"Court Bouillon", Bute St Seafoodie
"Caper Butter Sauce", Bute St Seafoodie
"Sauce Américaine", Bute St Seafoodie
"Watercress Sauce", Bute St Seafoodie