A weeknight dinner that tastes like a restaurant: a hard sear, a quick baste, and a sauce that takes about ninety seconds in the same pan.

There is a particular kind of fish supper I make when I want the evening to feel like more than it technically is. Nothing elaborate, nothing that takes the better part of an afternoon, just one good piece of fish, a hot pan, and a small amount of butter behaving rather better than it has any right to. Halibut is the fish I reach for. It has a firm, almost meaty texture and very little flavour of its own, which sounds like a fault and is in fact the whole point: it takes whatever you give it and gives it straight back, amplified.

The trouble with halibut, and the reason it has a slight reputation for being difficult, is that it goes from perfect to sawdust rather quickly. It is a lean fish, with none of salmon’s forgiving fat to fall back on, so the margin between done and overdone is a matter of a minute or two. I have made this exact recipe more times than I could count, and the method below is the one that has never once let me down. It is not complicated. It is simply precise in the two or three places that matter.

The two things worth doing properly are drying the fish and not fussing with it once it is in the pan. A fillet straight from its packet is wetter than you’d think, and a wet fillet steams rather than browns, which is how you end up with pale, sad fish instead of a proper crust. Pat it dry, properly dry, season it, and then leave it alone for fifteen minutes before it goes anywhere near the heat. Once it is in the pan, resist the urge to move it, peek at it, or nudge it about. It needs that stillness to build the crust that makes the whole dish.

The sauce is the reward for getting the fish right, and it could not be simpler. The same pan, a knob of butter cooked until it smells faintly of hazelnuts, a shallot, a scatter of capers, a squeeze of lemon. That is genuinely all of it, and it tastes like considerably more effort than it is. Capers and brown butter were made for each other, the nuttiness on one side and the salty, vinegary pop on the other, and lemon at the end ties the whole thing together before it can feel too rich.

Serves 2. About 25 minutes, start to finish.

Ingredients

• 2 halibut fillets, skin on, about 1.5cm thick
• 1 tsp fine sea salt
• 1 tbsp olive oil
• 60g unsalted butter
• 1 shallot, finely diced
• 2 tbsp capers, drained and roughly chopped
• ½ lemon, juiced
• A small handful of flat-leaf parsley, chopped

Method

1. Dry, season, rest. Pat the halibut fillets completely dry with kitchen paper, then season both sides with the salt. Leave on a plate at room temperature for 15 minutes. A dry fillet is the whole secret to a good crust.
2. A hot pan, skin-side down. Heat the olive oil in a heavy non-stick or cast-iron pan over medium-high heat until it shimmers. Lay the fillets in skin-side down and do not move them.
3. Sear and baste. Sear undisturbed for about 4 minutes, until the skin is deeply golden and crisp. Flip carefully and cook the other side for 3 to 4 minutes more, depending on thickness, basting the fish with the oil in the pan as it cooks. The fish is ready when it flakes easily but is still faintly translucent at the very centre. Lift onto warm plates.
4. Brown the butter. Wipe the pan if it looks burnt, then return it to medium heat. Add the butter and let it melt and turn a deep nutty brown, swirling the pan, about 1 to 2 minutes. Watch it closely; brown is what you want, black is not.
5. Build the sauce. Add the shallot and cook for a minute until softened, then stir in the capers and let them sizzle for thirty seconds. Take the pan off the heat and add the lemon juice, swirling to combine.
6. Finish and serve. Stir in the parsley, taste for salt, and spoon the sauce straight over the fish at the table.

This is a dish that wants very little beside it, because the whole pleasure is the fish and that small pool of sauce. Something to soak it up is the only real requirement. New potatoes, boiled until just tender and crushed lightly with a fork so the sauce has somewhere to go, are my usual choice. A pile of buttered spinach or some wilted greens does the same job with less effort, and the iron in the spinach plays nicely against the richness of the butter.