Heat the oven to 200C/180C fan/gas 6. Whisk most of the orange zest and all the juice, chilli, sesame oil and garlic in a small bowl, then season. Line a baking tray with foil, scatter over the fennel and tuck in most of the orange slices. Add the salmon on top, skin-side down, pour over the sauce, and top with the rest of the orange slices. Cook in the middle of the oven for 20 mins or until flaky and cooked through.

Meanwhile, boil the potatoes for 15 mins or until tender. Drain and tip back into the pan. Add most of the watercress and the olive oil, toss everything together with some seasoning and leave for a few mins for the watercress to wilt.

Whisk together the mayo, wasabi and remaining orange zest. Serve with the salmon and potatoes, and scatter over the remaining watercress to serve.