Pre-heat the oven to 200c.

Pan fry the halibut in butter and oil then pop in the oven for 5 minutes.

To make the sauce chop all the ingredients. Heat the butter in a pan, add the lemon juice, a dash of water and follow with the other ingredients.

To serve, place the fish onto a plate then spoon the sauce around, drizzle in a little herb oil, pop the watercress alongside with the mash.