Toast the sunflower seeds on a hot pan until lightly coloured. Set aside.
To make the salad: Chop the beetroot into cubes, approximately 2cm square. Place in a bowl and stir through the scallions. Combine all the ingredients for the dressing. Taste and season. Stir the dressing through the beetroot.
To make the Mustard Sour Cream: Place all the ingredients in a small bowl. Stir well to combine, taste and season. Set aside while you cook the mackerel.
To cook the mackerel: Heat a large frying pan. Add a little oil and a knob of butter. Add the mackerel fillets, skin side down and cook for 2-3 minutes then turn and cook on the other side for approximately 2-3 minutes.
To serve: Mix the rocket leaves through the beetroot, taste and season. Sprinkle over the sunflower seeds. Spoon a little of the salad onto each plate and lay the mackerel fillets on top. Spoon over a little Mustard Sour Cream. Serve the remaining salad on the side.
