Difficulty: Intermediate
Drain and trim the John Dory fillets, rinse under cold water, and arrange in an ovenproof dish with 1/2 chopped shallot, 1 knob of butter, and the white wine. Cook gently in the oven at 170°C (th. 5) for about 20 minutes. Drain the fish, reserving the cooking juices. Strain and reduce the juices to about the volume of a glass.
While the fish cooks, melt 1 knob of butter in a small sauté pan with the remaining chopped shallot and mignonette. Brown gently, deglaze with cognac, and reduce to dryness. Add the cream, simmer until the sauce thickens and ripples on the surface. Set aside.
For the sabayon: In a saucepan, combine the egg yolks with 2 tablespoons of water over very low heat. Whisk vigorously to emulsify, then gradually incorporate the reserved reduced cooking juices without stopping the whisking. Add the lemon juice.
Lift the John Dory fillets, remove the skin, and arrange on 2 warmed plates.
Stir the reserved cream reduction into the sabayon, season with salt and pepper; the mixture should be lightly frothy and sparkling.
Warm the plates in the oven for 1 minute, then generously coat the fillets with the sabayon sauce. Garnish with finely chopped chives.
Expert Tip: Substitute John Dory with sea bass or sea bream for a similar result at a lower cost.
Joëlle's Experience: Assembling the sabayon requires gentle, constant heat. If it curdles (separates), add a spoonful of cream and whisk vigorously to restore emulsion. For foolproof results, use a bain-marie.
