Preheat and Prepare: First, preheat your oven to 200°C (180°C fan). Lightly grease a 9x13 inch baking dish with the olive oil. This prevents the fish from sticking and makes clean-up much easier.

Pat the Fish Dry: Take your mahi mahi fillets and pat them completely dry with a paper towel. This is a crucial step! A dry surface allows the sauce to cling to the fish properly and helps it bake rather than steam in its own moisture.

Arrange the Fish: Place the dried fillets in the prepared baking dish in a single layer. Make sure there's a little space between each one to allow the heat to circulate evenly.

Make the Lemon Butter Sauce: In a small mixing bowl, whisk together the melted butter, minced garlic, the zest and juice of one lemon, the chopped parsley, salt, and black pepper. Stir until everything is well combined.

Sauce the Fillets: Pour this beautiful lemon parsley sauce evenly over the top of the mahi mahi fillets. I like to use a spoon to make sure each fillet is generously coated.

Bake to Perfection: Place the baking dish in the preheated oven. Bake for 15-18 minutes. The exact time will depend on the thickness of your fillets. I find that making a loose 'tent' with aluminium foil for the first 10 minutes keeps the fish incredibly moist, then I remove it for the final 5-8 minutes.

Check for Doneness: The mahi mahi is cooked when it is opaque all the way through and flakes easily when gently prodded with a fork. You can also check with a food thermometer – the Food Standards Agency advises cooking fish until the centre reaches 63°C.

Rest and Garnish: Carefully remove the dish from the oven. Let the fish rest in the dish for a minute or two. This allows the juices to settle back into the fillets. Garnish with fresh lemon slices and an extra sprinkle of parsley before serving.