Set the oven at 200C/gas mark 6. Scrub 400g of potatoes thoroughly, then slice them thinly – the thickness of a £1 coin would be about right.
Remove the leaves from 3 or 4 bushy sprigs of rosemary (you need a couple of tbsp) and chop finely.
Put the slices of potato into a mixing bowl and add 4 tbsp of olive oil, salt, black pepper and the chopped rosemary leaves. Toss the potatoes to coat them evenly with the oil and seasoning.
On a nonstick baking sheet, place the potato slices in a single layer, slightly overlapping here and there. Make sure the surface of the potatoes is covered with a little oil, then bake for about 25-30 minutes until pale gold and lightly crisp here and there. Roughly chop the fronds from a couple of sprigs of dill or fennel.
Remove the baking sheet from the oven, then divide the potatoes between 2 shallow bowls or plates. Scatter with a couple of tsp of drained capers.
Place 2 rollmop herrings on each, trickling a little of the rollmop juices over the potatoes. Scatter the chopped dill over and eat while the potatoes are still hot and crisp. Serves 2. Ready in 45 minutes
Ideally, the cooked potatoes will be crisp in parts and softer in others.
This is also a good way to use smoked mackerel, breaking it into large, juicy pieces on top of the potatoes, instead of the rollmop herrings.
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