Use a knife to remove the skin from the oranges, then cut between the white membranes to loosen the orange segments. Once all the segments have been removed, squeeze the remaining piece of orange over a bowl to remove the juice, set aside.

Remove the skin from the mackerel and break the flesh into bite sized pieces. Break the chicory into leaves. Arrange the watercress, chicory, mackerel and orange segments in a large salad bowl.

Whisk the reserved orange juice, oil, mustard and honey together with a little salt and freshly ground black pepper. Drizzle over the salad and serve.