This is a beautifully fresh and quick dish to cook when you feel like a light seafood lunch or supper. Scaled up, it is also a real crowd-pleaser. The plaice and mussels pair beautifully with the bright green, earthy broad beans and lemony brown butter. I love using toasted buckwheat in dishes – it is a really quick and easy way of adding another texture to a dish.

Serves: 1

Prep time: 10 minutes

Cooking time: 15 minutes

50g buckwheat

Salt

100g mussels in their shells, beards removed

100ml white wine

200g baby spinach, washed

Sunflower oil

1 whole plaice, filleted and skinned

40g butter

1/2 lemon, juiced

100g broad beans (fresh or frozen), podded, blanched and peeled

Cook the buckwheat in salted simmering water until it has no more bite to it. Strain the water and, in a warm frying pan on a low heat, gently fry the buckwheat until it is golden brown with a good crunchy texture (it should not be chewy), then set aside.

Place a small pot over a high heat; have the mussels, white wine and pot lid ready. When the pot has reached a high temperature, put the mussels inside, cover with white wine and put the lid on. Leave for approximately one minute, then remove from the heat and pour the mussels into a colander over a bowl. Allow to cool.

Once cooked, pick the mussels out of the shells and set aside (discard the shells). If any mussels haven’t opened, discard them too as they should not be eaten.

Warm a small pot and saute the baby spinach. Once wilted, place the spinach on to a plate. Heat a glug of oil in a non-stick frying pan, season the plaice with salt and add it to the pan. Cook for approximately two minutes, until it is almost fully cooked, then take off the heat.

Carefully flip the fish over, then remove from the pan and place on top of the spinach.

Put the pan you cooked the fish in back on the stove and add the butter, allowing it to melt. It will start to bubble and turn golden brown.

Before it starts to burn, add the lemon juice, and take it off the heat. Add the mussels and broad beans into the butter and lemon, then pour it all over the plaice and spinach.

To finish, sprinkle with toasted buckwheat.

Roberta Hall-McCarron is the chef at the Little Chartroom, Edinburgh.

• The Guardian and Observer aim to publish recipes for sustainable fish. For ratings in your region, check: UK; Australia; US.