When buying the fish, ask your fishmonger to gut and scale it, but do not remove head and tail. At home, rinse the fish under fresh water and then pat it dry with kitchen paper.
Cut a large piece of foil so that you can wrap your fish later. In the centre of the foil put a layer of greaseproof paper, roughly of the same length as your fish. Put some drops of olive oil on the greaseproof paper.
Spread the olive oil all around the greaseproof paper (use your fingers or a little brush).
Slice the potatoes (thin slices) and lay the slices as shown in the picture. Then, drizzle some olive oil over the potato slices. The potato helps to absorb part of the liquid that may form in the bottom during the cooking.
Make three diagonal cuts onto the top side of the fish.
Brush the inside of the belly with olive oil.
Stuff the belly with the anchovy fillets. I am not seasoning the inside of the fish belly with salt because the anchovy fillets are already salted. However, feel free to season with black pepper if you wish to do so.
Put half of the capers inside the gills.
Put the remaining capers inside the fish belly.
Next, cut three thin slices from the lemon and put each slice into each of the cuts you previously made.
Drizzle some olive oil over the fish.
Season the outside with salt.
Season the outside with black pepper.
Close the wrap, seal it folding the sides and put it onto an oven tray. Pre-heat the oven to 200°C (400°F). When the oven is hot, put the tray into the oven and cook the fish for about 35 minutes.
Once the fish is cooked, drizzle with some good quality olive oil and sprinkle with parsley (the fish may be served on the wrap).