Gurnard is an underrated fish often overlooked in favour of more popular species such as cod, sea bass and turbot. This means that the price per kilo is significantly lower than these other fish and it is also a much more sustainable choice. Gurnard is full of flavour and benefits from being cooked sous vide because all the moisture is retained during cooking.
For extra flavour, try adding various herbs and spices to the bag; try thyme, rosemary and garlic or lemon zest.
You can use butter in place of oil for a richer flavour; beurre noisette complements the flavour of the fish particularly well.