First cure your fish. Combine all the ingredients for the cure in the bowl of a food processor and blitz until you have a purple paste. Place the fish into a large bowl or baking tin and cover all over with the cure. Cover with cling film and refrigerate for at least 2 hours, preferably 4. While that’s curing, you’re going to lightly pickle the blackberries. Bring the vinegar to the boil with the salt and bay in a non-reactive pan. Add the blackberries and set aside
When the fish has cured, rinse it gently under a softly running tap and dry with kitchen roll. Leave on the kitchen roll to dry while you make the remoulade
To do this, combine the sliced ingredients in a bowl and season with salt and pepper. Mix the mayonnaise, Dijon mustard, olive oil together along with 1 tbsp of the blackberry vinegar (from pickling the blackberries), and use it to dress the remoulade. Add the capers, pumpkin seeds and soft herbs and combine until everything is lightly and evenly coated. Drain and add the blackberries, reserving the blackberry-infused vinegar for other occasions (lovely dressing for salad mixed with olive oil)
Heat a large, heavy-bottomed non-stick frying pan or cast iron skillet over a medium-to-high heat with 1 tbsp. of olive oil and knob of butter, garlic and thyme. Place the fish in the pan and cook, without moving it (you want it to create a self-sealing crust) for three or so minutes, baste with the melted butter. When it comes away from the pan naturally, flip it over and finish for a couple more minutes, continuing to baste it. Once just cooked through, divide the fish between plates with the remoulade. I like to season the fish with a little more of the vinegar (as you would lemon juice).
Garnish with more fresh herbs.
You need to use really fresh fish for this, so make sure it’s not fishy at all and very clean and bright