Lightly oil 4 sheets of baking paper, each large enough to make a parcel. Place 4 thick fillets white fish, such as pollock, on top of the paper, season with salt and pepper, add a squeeze of lemon juice and a few fennel fronds. Gather up the sides of the paper and fold over at the top to make 4 sealed parcels.

Place the parcels on a baking sheet and roast on the bottom shelf of the oven, below the potatoes and vegetables, for 16–20 minutes, depending on the thickness of the fillets, until the fish flakes easily. Serve on top of the potato mixture in place of the scamorza and pumpkin seeds, with the fennel fronds and the caper and herb oil drizzled over the top.