By William Lander, Shaun Searley and Daniel Morgenthau
Adding chopped boiled eggs calms down the acidity of the capers and gherkins here, making for a more rounded sauce. Do take the fish out of the fridge 30 minutes before you want to cook it. Raising the temperature slightly beforehand puts less stress on the fish during the cooking process, meaning it cooks more evenly.
Make the gribiche a day in advance if you can, to let the flavours really fuse together. Hard-boil the egg for 10 minutes, then chill in iced water. Peel and finely dice the shallot along with the cornichons. Finely chop the herbs. Peel and chop the egg, then add to a bowl with the diced shallot and cornichons, the lemon zest and juice, chopped herbs, capers and mayonnaise. Combine gently, then