Soften the shallot, the mushroom, and the leek in the butter being careful not to brown, add the white wine and reduce to a table spoon, now add the fish stock and tarragon and reduce to 3 tablespoons. Pass through a fine sieve, add the cream and bring to a simmer and check the seasoning. Now add the finely diced tomatoes, Squeeze half a lemon to taste.
To make the pea pure
Soften the shallots in a small pan being careful not to let them brown. Then in a food processor put the peas, goat’s cheese, mint leaves, salt and pepper and softened shallots and process. Season well and put to one side until required and lightly reheat.
To make the beetroot crisps
Heat the oil in a frying pan to 170c and deep fry the beetroot slices until crispy.
To cook the fish
Fry on one side for one minute then turn over and fry for a further 30 seconds on the other side. Reheat the sauce and the pea puree and serve with a sprig of chervil.