We cooked this dish after [my husband] Neil had been out fishing and had caught a fresh-water trout. It’s the stuffing that makes this such a delicious dish; just soften onions and garlic in butter and mix it with the breadcrumbs, fresh herbs, almonds and slices of lemon. Trout is quite forgiving so you can use any mix of herbs you fancy. The stuffing would work just as well with a whole salmon or with small sea breams or seabass.
I really like cooking fish en papillote, and you could certainly use the sealed paper technique here – just cut a big sheet of baking paper to line the oven tray. Once the fish is in and drizzled with the oil, gently bring the sides together, being careful not to wrap the fish too tightly, then crimp to seal and cook as per the instructions below.