Halibut are enormous flatfish; they can weigh as much as 800 pounds, and 100-pounders are common. They are related to the flounders and soles commonly found in fish markets and restaurants.

The majority of flatfish are caught in the wild, but the premium fish of high value, such as halibut and turbot, are successfully farmed. A very small proportion of Dover sole is also farmed.

Halibut is a delicious, firm-textured flat fish. Take care not to overcook it as it will dry out and spoil the texture. Preheat the oven to 220C/425F/Gas 7. Heat 50g/1¾oz of the butter in an ...