1. Brush the halibut fillets with olive oil. Season the halibut fillets with Old Bay Seasoning. Heat your grill to medium high heat. Oil the grill with an oiled rag and grill the halibut until the internal temperature reaches 140℉.
2. Bring orange juice, wine, shallots, cream and vinegar to a simmer in a heavy saucepan. Add cardamom and tarragon and continue to simmer until the volume is reduced by half. Reduce the heat to low and whisk in the butter one piece at a time, lifting the pan from the heat occasionally to cool the sauce. Melt each piece of butter before adding the next. Keep the sauce in a metal bowl over a saucepan of hot water until ready to serve.
3. To plate, drizzle citrus butter sauce over half the fish until it pools underneath it. Serve with your choice of accompaniment.