Steamed fish doesn't exactly have the best reputation outside of spas and health-centric restaurants, but in the hands of Hugh Fearnley-Whittingstall and Nick Fisher, gently cooked fillets are anything but dry and boring. Dubbed "steam-braising" in The River Cottage Fish Book, their method consists of using a rich (read: butter and olive oil) sauce full of herbs, wine, and garlic to gently steam (and braise, I suppose) small medallions of sea bass (or most other white, flaky fish). The emerges from the pan tender and contributes its subtle brininess to the sauce.
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In The River Cottage Fish Book, Hugh Fearnley-Whittingstall and Nick Fisher offer a slight variation on the standard stuff-the-trout-with-herbs-and-grill-it method. Instead of picking soft, delicate herbs, they call for overgrown, wild fennel. Then, they not only place the floral, herbaceous plant into the fish cavity (with garlic and bay, of course), but also use the woodiest herbs as a kind of grate for cooking the fish. These woody stems smolder as the fish cooks, adding another layer of smoky flavor to the fish.
Roasting whole fish has got to be one of the simplest ways to impress a table full of diners—throw in a fancy British fish name or two and you've got yourself a winner of a party. Plaice is one of the most common flatfishes eaten in Europe, and lucky for us, it and some of its more familiar neighbors are being fished in sustainable manners here across the pond.* In The River Cottage Fish Book, Hugh Fearnley-Whittingstall and Nick Fisher espouse the wonders of whole plaice, praising its subtle, sweet salinity. To bring out the sweetness of the fish, they roast cherry tomatoes alongside, which caramelize and burst in the hot oven, adding their own luscious nectar to the roasting pan.
Squid are kind of a gateway shellfish. They're not terribly fishy and they're relatively easy to clean and prepare.
Both salmon and mackerel are sweet, oily fish, so it's an easy swap to make. Whole mackerel comes cheap at most fish markets, and they're (fairly) easy to fillet following the hilariously detailed instructions in the River Cottage Fish Book. It's a unique alternative to gravlax that you can make with just a 48-hour cure.