To make the sauce, combine the vinegar, peppercorns, and tarragon in a small saucepan and heat over medium heat until reduced by half, 2–3 minutes. Strain through a fine-mesh sieve and set aside.
Put a cube of the butter in the top pan of a double boiler over (not touching) gently simmering water in the lower pan. (Or rest a heatproof bowl in the rim of a saucepan over simmering water.) Whisk the egg yolk in a small bowl, add it to the melted butter, and whisk together. Then add the remaining butter, a cube at a time, waiting until each cube melts and is whisked into the mixture before adding the next cube. Continue to whisk until all the butter is fully incorporated and the sauce has thickened, then remove from the heat, whisk in the lemon juice, and season to taste with salt. Cover with plastic wrap, pressing it directly against the surface of the sauce to prevent a skin from forming.
Pat the fish fillets dry with paper towels and place them, skin side up, on a plate. Sprinkle the skin side evenly with the salt and let stand for 5 minutes. Select a heavy-bottomed frying pan large enough to accommodate the fillets in a single layer, add 2 tablespoons of the butter, and melt the butter over medium heat. Add the fillets, skin side down, and cook until lightly browned, 3–4 minutes. Turn the fillets over and cook the flesh side for 2 minutes. Flip them back over so they are skin side down and add the remaining 2 tablespoons butter to the pan. When the butter melts, tilt the pan, then use a spoon to collect some of the melted butter and spoon it liberally over the fillets three or four times. At this point, the fillets should be just cooked through. If the sauce has cooled, reheat it gently over simmering water, whisking constantly. Serve the fish with the sauce on the side.
DAISY: Oh my god! What’s happened?
DAISY: It’s curdled and it’s got to go up in a minute! Oh my Lord!
˜ SEASON 3, EPISODE 5
© 2019 All rights reserved. Published by Weldon Owen.