This is a brilliant one-tray dinner. Roasted fennel and potatoes are a magic combination, as are the fresh herbs and salmon. Scoring and stuffing the salmon is a great little trick you can use on any type of fish.
Preheat your oven to 220°C/425°F/gas mark 7. Bring a large pan of salted water to the boil. Halve the potatoes lengthways and trim the fennel bulb, reserving the leafy fronds for garnishing later. Cut the fennel bulb into eight wedges, add these to the salted water with the halved potatoes and parboil for around 6 minutes.
Drain the vegetables in a colander and leave to steam-dry for a minute. Transfer to a large roasting tray and season well with salt and pepper. Sprinkle over half the chopped parsley and all of the garlic, dot over the butter and drizzle well with olive oil. Toss everything together in the roasting tray, then shake it out so it is in one even layer. Cook in the oven for about 30 minutes, or until golden.
While the vegetables are roasting away in the oven, you can start preparing the salmon fillets. Pinch the fillets so they plump up and use the length of a knife to score the skin side of them. You want to score about 1cm down into them. Not only will this help all the lovely flavours get right into the fish, it will also help it cook more quickly. Season both sides of the fish well and stuff the remaining chopped parsley and the mint leaves into the scores. Mint goes brilliantly with oily fish, such as salmon.
Once the potatoes are nice and golden, take them out of the oven and sprinkle the grated Parmesan over them. Give everything a bit of a jiggle, then lay the salmon, skin-side up, on top. Sprinkle the lemon zest over the top, drizzle with olive oil then cook for 15 minutes.
Just before the salmon comes out of the oven, chop the reserved fennel fronds. Sprinkle them over the finished dish, then serve it in the middle of the table with some wedges of lemon and let everyone tuck in.