Place the potatoes in a pan of cold, salted water and bring to the boil. Cook until tender and then drain and leave to steam for a few minutes before crushing lightly with a fork.
Pick and chop the parsley leaves. Heat a frying pan over a medium heat and add the lardons. Cook until golden brown and crispy. Add the lardons and the parsley to the potatoes and mix together with a fork. Season with salt and pepper.
Wash and roughly pick the watercress, discarding any chunky stalks.
For the dressing: zest and juice the lemon. Combine the lemon zest and juice with the mustard and then slowly whisk in the two oils.
Dress the watercress leaves with the lemon and mustard dressing.
Fillet the mackerel if necessary and remove any pin bones.
Heat a frying pan to hot and add the sunflower oil. Add the fish to the pan skin-side down and cook for 3 minutes. Turn the fish over to finish cooking.
Plate the potatoes using stainles steel serving rings. Place the mackerel on top and finish with a neat pile of the watercress salad. Add a drizzle of olive oil to serve.
«Try replacing the bacon lardons with capers, or olives to five a Mediterranean flavour to this dish. Remove any excess oil from the lardons by placing them on kitchen paper once cooked.»