• 1 lemon, rinsed and scrubbed
• 700 g (1 lb 9 oz) potatoes, scrubbed
• 185 ml (6 fl oz/¾ cup) warm milk
• 50 g (1¾ oz) butter
• 70 g (2½ oz) pitted green olives, halved or quartered if large
• 2 tablespoons olive oil
• 2 garlic cloves, peeled and lightly squashed with the flat of a knife
• 4 persico (perch) fillets, about 170 g (5¾ oz) each
• 1 heaped tablespoon small capers in vinegar, drained
• 60 ml (2 fl oz/¼ cup) water

Grate about a teaspoon of rind from the yellow part of the lemon. Keep aside. Cut 4 slices of lemon, a few millimetres (fractions of an inch) thick, from one end and then squeeze the juice from what’s left. Keep aside.

Meanwhile, boil the potatoes in their skins in boiling salted water until they are soft all the way through when you pierce them with a fork. Drain and when cool enough to handle, peel and then put back in the pot. Mash them, adding the lemon rind. Add the warm milk and butter and turn through well. Stir in the olives and season with salt and pepper. Keep warm.

Heat the oil in a large non-stick frying pan, add the garlic and fish fillets and sauté over medium heat until they are a bit golden underneath. Turn them over, add the lemon slices to the pan and fry until the fish is golden underneath once more. Turn the lemon slices too, so they are golden and caramel on each side. Season with salt and pepper, add the lemon juice and scatter the capers over the fish. Put the lid on and simmer for a minute more, until the lemon juice is a syrupy sauce and the fish is cooked through. Remove the fish and lemon slices to warm serving plates. Add the water to the pan and return to the heat. Simmer, uncovered, to reduce a little. Pour over the fish and serve with an extra grind of pepper and a pile of mash on the side.