Mackerel, mustard, spinach & lemon salad

Boil or steam the potatoes until just done. Set aside. While this is taking place, whisk the vinegar, garlic and wholegrain mustard and then slowly add the olive oil and finally the tarragon. It should emulsify.

Cut the potatoes in half and mix the potatoes with the dressing while they are still warm. Season well.

Let the dressing soak in a bit and then mix in the spinach. Once that has a bit of dressing on it, arrange on a platter with the mackerel on the top.

Dust the whole thing with lemon zest and serve.