For the salmon

1. Heat the oven to 150 C fan/gas 4.
2. In a large shallow roasting tin or baking tray, scatter the lemon slices, thyme sprigs, and dill stalks.
3. Season the salmon with a pinch of salt and pepper and rub half of the olive oil all over the fish. Lay the salmon skin-side up on top of the lemon and herbs.
4. Roast for 40-45 mins until the fish feels firm and a corner of skin peels away easily.

For the potatoes

1. While the salmon is cooking, place the potatoes into a pan of cold salted water and bring to the boil. Reduce the heat to a simmer and cook for 10-15 mins until just tender.
2. When drained, separately mix the mustard, lemon juice and olive oil together in a large bowl, and season with salt and pepper. Tip the hot potatoes into the bowl and toss to coat in the dressing and set aside.

To serve

Carefully lift the salmon onto a serving platter, or alternatively it can be served in the roasting tray. The salmon can also be eaten warm or chilled.