Halve the onions, cut into strips and sauté with a little butter and sugar. Deglaze with Noilly Prat and braise covered in the oven at 150 °C for approx. 12 minutes.
Mix (thicken) with chicken stock and ice-cold butter and season to taste.
Season the fish stock with salt, curry and Noilly Prat. Reduce a little (let it boil down), stir in some ice-cold butter and put in the halibut. Let steep over moderate heat just to keep the fillets nice and glazed on the inside.
Arrange braised onions in plates as deep as possible, place halibut fillets on top and garnish with chives.