Preheat oven to 425°F/220°C, combi steam setting. If your oven has variable steam settings, choose 50%. If not, don’t worry! Just set to combi steam at the correct temperature and the oven will work out the steam for you.
Combine the potatoes, 2 tablespoons olive oil and half the salt in a shallow pan. Toss well to coat and cook for 20 minutes.
1 lb baby potatoes, 1½ tsp flaky salt, 4 Tbsp olive oil
Remove the potatoes from the oven and push them to the edges of the pan. Add the salmon to the gap you’ve made in the center and rub with the remaining oil, pepper and remaining salt. Return the pan to the oven and cook until the salmon is just done to your liking, about 8 minutes.
4 Tbsp olive oil, 1 tsp black pepper, 1.3 lb salmon, 1½ tsp flaky salt
While the salmon cooks, make the burnt butter. Put the butter into a medium saucepan set over medium-high heat. Allow the butter to melt and then sizzle and bubble until the milk solids turn brown and it smells nutty. Be careful as it’ll go from golden brown to black very quickly! As soon as it’s done, pour into a heatproof bowl and stir in the lemon zest and a tablespoon of the juice.
5 Tbsp salted butter, 1 lemon
Mix the mustard and cider vinegar together and toss through the arugula/rocket.
1 tsp dijon mustard, 1 Tbsp cider vinegar, 2 cups arugula
When the salmon comes out of the oven, pour the burnt butter over the top and serve immediately, with the potatoes and dressed greens on the side.