Directions

1. Place the potatoes into a saucepan and put a full kettle on to boil. Pour over the boiling water, add a generous pinch of salt, and cook over a high heat for 5 minutes. Drain and return the potatoes to the pan to steam dry for 5 minutes.
2. Meanwhile, preheat the oven to 220C/200C Fan/Gas 7. Add the olive oil to a roasting tin and place in the oven to heat for 5–10 minutes.
3. Carefully remove the hot tin of oil from the oven, then tip in the potatoes and season with salt and pepper. Toss to coat the potatoes in the oil then spread out in a single layer and return to the oven. Cook for 25 minutes (shaking halfway) until golden and crispy.
4. While the potatoes cook, make the rest of the salad. In a large mixing bowl, combine the soured cream, mayonnaise, Dijon mustard, honey, vinegar, garlic, red onion and cornichons. Season with salt and pepper and mix well.
5. Add the spinach to the bowl and as soon as the potatoes are cooked, place them on top. Cover the bowl and leave for a minute (the heat will wilt the spinach a little) and then add the mackerel pieces and the herbs. Toss everything together. Taste and add more salt and pepper, if necessary, before dividing between two plates and serving immediately, with extra herbs scattered over.