Dry-Aged Cured Trout with Yuzu Kosho Beurre Blanc and Trout Roe

This is a decode of one of the signature plates at JÖRO in Sheffield — trout that's been cured and dry-aged until it eats more like something between sashimi and confit, seared hard on the skin and set over a beurre blanc spiked with yuzu kosho. The roe on top isn't decoration: every bean of it is a little salt-and-brine seasoning bomb that does the work a finishing salt would. And the sansho leaf oil, flecked green through the pale sauce, carries the citrus-tingle note that ties the whole plate to Japan.

None of this needs restaurant equipment. The dry-aging happens on a rack in your fridge overnight, the beurre blanc is a classic French emulsion with one spoonful of Japanese seasoning stirred in, and the fish cooks in one pan in under five minutes.

How to cook

The cure and the overnight dry is the whole point of this dish, so don't skip it. Salt and sugar pull moisture from the fish and season it to its core in two hours; the uncovered rest on a rack afterwards lets the fridge's dry air do a gentle, twelve-hour version of what JÖRO's aging fridge does over days. The flesh firms and concentrates, the surface tacks up into what charcutiers call a pellicle, and the skin dries out so completely that it crisps in the pan like it was born to. If you can give it a full 24 hours, even better.

The sansho leaf oil is the plate's perfume. Fresh sansho leaves (kinome) are a specialist buy — Japanese grocers sometimes carry them in spring and summer — so the recipe gives you an honest substitute: parsley for the green, ground sansho pepper for the tingle. Either way the method is the same: a ten-second blanch to set the colour, an ice bath, a hard squeeze, and a long blitz with neutral oil. Strain it slowly through a coffee filter and don't press — you want a clear, vivid green oil, not a purée.

The beurre blanc follows the classic playbook — a sharp shallot reduction strained smooth, a spoonful of cream as insurance, then cold butter whisked in off the heat until it's a pale, glossy emulsion. Strain before the butter goes in, not after: you want the shallot's flavour without its texture, and a finished emulsion doesn't take kindly to being pushed through a sieve. The yuzu kosho goes in at the very end, and this is where you should taste as you go. Yuzu kosho is fermented yuzu zest, green chilli, and salt, and brands vary wildly in heat and saltiness: one teaspoon might be perfect, two might blow the sauce out. You're looking for a butter sauce with a citrus glow and a slow warmth behind it, not a chilli sauce. Remember the roe is salty too, so keep the seasoning a touch under where you'd normally land. Hold the finished sauce somewhere warm — over a pan of just-steaming water is ideal — because a beurre blanc splits if it boils and sets if it chills.

The fish itself is the fast part. Because the cure has already seasoned it and the fridge has dried the skin, all the pan has to do is crisp and warm. Medium-high heat, a film of oil, skin-side down, and a gentle press for the first half minute so the fillet doesn't curl away from the pan. Leave it alone for three to four minutes — you'll see the opacity creep up the side of the fillet — then flip, add the butter, and baste for under a minute off the heat. Cured trout wants to be served just warm and blushing at the centre, around 48-50°C; take it further and you lose the silky texture the cure bought you.

Bonus points

• Age it longer: With very fresh fish and a clean fridge, the uncovered rest can stretch to 48 hours. The flavour deepens noticeably and the flesh turns denser and more savoury — the closest a home fridge gets to true dry-aged fish.
• Cure a whole side: Double the cure and do a whole side of sea trout, then portion after the overnight dry. The centre cuts go to this dish; the thinner tail ends, sliced raw, are a cook's-treat crudo with a few drops of the sansho oil and a little roe.
• Marinate the roe: Stir the trout roe with a teaspoon of soy sauce and a few drops of yuzu juice fifteen minutes before plating. The seasoned roe has more depth and ties into the sauce.
• Torch the skin: After basting, hit the crisp skin with a blowtorch for a few seconds until it blisters and chars at the edges — the smoky, just-burnt note is very JÖRO.
• Make it a smaller course: Halve the portion size and serve it as the fish course of a tasting menu — the sauce and oil quantities already stretch to six or eight smaller plates.

Serving

Serve this in warmed shallow bowls so the beurre blanc pools rather than runs. Spoon the sauce first and give it a moment to settle, then dot the sansho leaf oil through it in an irregular scatter — a squeeze bottle gives you the neat JÖRO-style specks, but drops off a teaspoon look just as alive. The trout sits in the middle, crisp skin up, with the roe spooned generously over the top so it cascades a little down one side, and a single sansho leaf laid on the diagonal.

This is a composed course, so resist the urge to add a starch to the plate — if you want to round it into a fuller meal, serve steamed rice or new potatoes in a bowl alongside and let people help themselves.

To drink, the sauce calls the shots: you want acid and texture. A good Chablis or a dry German Riesling handles the butter and the yuzu in equal measure, and a crisp junmai sake, served cold, leans into the dish's Japanese accent beautifully. If you're pouring something sparkling, a blanc de blancs with a few years on it is a quiet showstopper against the roe.