Ingredients

Step by step

1. First cut the skin and pith off the oranges and cut out the segments with a small, sharp knife, over a bowl to catch any juice. Set the segments aside and squeeze the juice from the pithy flesh remaining. Whisk the balsamic vinegar, 3 tablespoons of olive oil and 1 teaspoon of mustard into the juice, then stir in the beetroot, butter beans and most of the dill.
2. Score the mackerel skin diagonally in a couple of places, then brush the skin with the remaining 2 teaspoons mustard and some seasoning. Spread the sesame seeds on a plate, and press the mackerel, mustardy- skin-side down, in the seeds to coat lightly. Set aside on a plate
3. Heat a couple of teaspoons of oil in a nonstick frying pan over a medium heat. Fry 2 mackerel fillets at a time. Place them skin-side down and cook for 2 minutes until the sesame seeds are golden, then turn and cook for another 1-2 minutes until cooked through. Transfer to a plate, wipe out the pan with kitchen paper, refresh the oil and cook the remaining fillets in the same way.
4. To serve, place a mackerel fillet skin-up on 4 plates. Place a pile of watercress to the side, mix in the orange segments and any juice, then spoon the dressed beetroot and beans over the salad, and scatter over a little more dill.