Debora Robertson’s updated Sunday lunch: whole roast sea bass recipe

A lot of people are intimidated by cooking fish, but it’s the first thing they order when they go to a restaurant. It’s understandable. It isn’t cheap, and you can overcook it easily and it usually needs to be cooked at the last minute. But cooking a whole fish takes away those pressures and it looks really wonderful when you bring it out to the table. If you have a crowd, you can easily do two trays – You can also do all the prep a couple of hours in advance and just start cooking about 45 minutes before you want to eat. The fish has a better flavour when it’s cooked on the bone too.

Serves 4-6, depending on what else you are serving
extra virgin olive oil 80ml, plus a little more to finish – use your good oil
lemon 2 strips of zest, about 6cm, carefully pared from an unwaxed lemon with a sharp vegetable peeler, making sure you don’t remove any bitter white pith
fennel seeds 1 tsp, lightly crushed
waxy potatoes 1kg, such as anya or charlotte
fennel 1 small bulb, about 350-400g
fresh lemon thyme a small bunch, about 6-7 sprigs
torpedo shallots 2, about 140g, halved and thinly sliced
fresh tarragon 5 sprigs
bay leaves 4
unwaxed lemons juice of 2
salt and freshly ground black pepper
sea bream or sea bass 1 large, about 1kg, scaled and gutted – get the fishmonger to do this for you
lemon wedges to serve

Put the oil in a small pan with the lemon zest and fennel seeds. Warm gently, without letting it simmer, for 5 minutes, then remove from the heat and cool.

Preheat the oven to 180C fan/gas mark 6.

While the oil is cooling, prepare the vegetables. Peel the potatoes and slice them thinly. If you’re a mandolin kind of person, use that. I am not a mandolin kind of person and after a long, bloodstained history of pretending that I am, so I hope you won’t mind if I will just sit quietly over here with a sharp knife and a chopping board, and do the best I can to get skinny little slices of potato without having to ruin Sunday lunch by rushing to A&E. I did once go to Sunday lunch at our friends Fred and Kay’s, and Fred cut his hand on a tin of foie gras. He ran off to A&E, got himself stitched up and was back before the main course was served, and despite his admirable sangfroid, it’s not ideal.

Quarter the fennel, remove the tough core, then slice the quarters thinly (see above). If your fennel has fronds, save some to put inside the roasting fish. Remove the leaves from 4-5 sprigs of the thyme.

Brush a little of the seasoned oil all over the inside of a roasting tin or ceramic gratin dish which is large enough to hold the fish. Put the potatoes, fennel and shallots into the tin with the thyme leaves, 4 sprigs of the tarragon and 3 of the bay leaves, and pour over about 3 tablespoons of the oil (hold back the strip of lemon zest, but let some of the fennel seeds drop in there).

Trickle on the lemon juice and season with a teaspoon each of salt and pepper. Give everything a very good stir, then pat it all down into an even layer. Cover it tightly with foil and put it into the oven to roast for about 30-40 minutes, removing it once to turn everything over before covering it again and returning it to the oven. When all the vegetables are quite tender, remove the foil and whack the oven up to 200C fan/gas mark 7. Make sure it’s up to temperature before you put the fish in.

Prepare the fish by cutting 3 or 4 diagonal slashes almost to the bone on both sides. Place the fish on top of the vegetables and brush it all over with the oil, inside the cavity and into the cuts, and all over the skin. Put the lemon zest strips, the remaining thyme sprigs, tarragon sprig and bay leaf inside the fish, along with some of the fennel seeds and any fennel fronds you have. Season the fish with salt and pepper and return the whole tray, uncovered, to the hot hot hot oven.

Roast for 20 minutes, until the fish is just cooked through – to test this, press a small, sharp knife into one of the cuts and if you can gently scrape some of the flesh away from the bone without resistance, it’s done. Rest for 5 minutes before serving (but make sure the plates are warmed), with a little more of the fruity olive oil trickled over the top.

From Notes from a Small Kitchen Island by Debora Robertson (Michael Joseph, £26)