Preheat your oven to 190°C/Fan 170°C/Gas 5 and put a roasting tin on the top shelf to warm up. Scrub the salad potatoes and chop them into 2-3cm chunks. Take the roasting tin out of the oven and add the potatoes. Add 1 tbsp olive oil and a pinch of salt and pepper. Slide back into the oven and roast the potatoes for 20 mins.

While the potatoes roast, peel the onion and slice a sliver off 1 side so the onion sits flat on your chopping board. Slice it into thin rings. Add the onion to a bowl with 1 tsp olive oil and a pinch of salt and pepper. Toss together and set aside.

Tip the yogurt into a separate bowl. Trim and finely chop the white part of the spring onion. Add it to the yogurt. Grate in the lemon zest. Finely chop the chives and add them to the bowl with a pinch of salt and pepper. Stir together.

When the potatoes have roasted for 20 mins, take them out of the oven and add the onion rings to the tin. Toss to mix, then return to the top shelf of the oven. Roast for another 10 mins.

Line a baking tray with baking paper. Lay the salmon fillets on the baking tray, skin-side down. Spread 3 tbsp of the yogurt mixture over each fillet. Set the rest of the yogurt aside for later.

Slide the salmon into the oven on the shelf below the potatoes and bake for 10 mins. The potatoes will roast for 40 mins in total – you'll know they're ready when the spuds are golden and crisp. The salmon will flake easily when pressed with a fork.

While the salmon roasts, squeeze the juice from half the zested lemon into a bowl and whisk with 1 tsp olive oil and some salt and pepper to make a dressing. Toss the salad leaves with the dressing.

When the salmon is ready, pop it onto 2 warm plates and serve with the potatoes, the remaining lemon and chive yogurt and the dressed salad leaves on the side.