Preheat oven to 50°C/120°F. Place rack over a tray.

Season fish: Sprinkle fish with salt and pepper.

Cook fish: Heat oil in a large non stick skillet over medium high heat. Cook fish in two batches until golden, 2 minutes on each side, or until the internal temperature is 55°C/131°F. (Note 4)

Keep warm: Place fish on rack, and place in the oven to keep warm.

Discard oil: Tip out excess oil from the skillet but don't wipe clean.

Reduce wine: Add eschalot, white wine, lemon juice, vinegar, salt, pepper, sugar to the pan. Bring to simmer (still on medium high) and reduce by half (~3 minutes).

Simmer cream: Add cream, simmer for 2 minutes.

Finish with COLD butter: Turn heat to low and add cold butter one cube at a time while mixing with wooden spoon. Once all the butter is incorporated, the sauce should be thickened, satiny and beautifully glossy.

Optional strain: Strain the sauce through a sieve (discard eschalot), then pour it back into the pan.

Fish in sauce: Place fish back into the pan in the sauce. Spoon some sauce over the fish, leave for 30 seconds.

Serve: Transfer fish onto serving plates. Spoon sauce over each fish, sprinkled with parsley if desired. Pictured with a side of pea puree (great colour splash!).