Heat your oven to 180°C/Fan 160°C/Gas 4. Scrub your potatoes and cut them so they’re all roughly the same size, while keeping as many as whole as possible. Peel and thinly slice the chioggia beetroot as thinly as possible.
Pop the potatoes in a pan and cover with cold water and a pinch of salt. Bring to the boil, cover and simmer for 10-15 mins till the potatoes are tender.
Drain the potatoes. Add them to a roasting tin. Drizzle with ½ tbsp oil and seasoning. Add the beets. Toss together. Cook in the oven for 20 mins.
Peel and thinly slice the shallot. Pick the leaves from the dill. Zest and juice the orange and lemon.
Heat a third of the butter in a large frying pan with 1 tsp oil. Add the trout, skin side down. Cook for 2 mins. Pour in the orange juice and zest and 1 tbsp of the lemon juice. Bring to a simmer then add all the butter and plenty of black pepper. Put on a lid and cook for 5 mins.
When the fish is cooked, add half the dill and stir it together. Carefully lift out with a fish slice or spatula and place on a plate. Pour the orangey butter into a small jug. Cover both with foil.
Using the same pan, add the shallots and fennel seeds with a pinch of salt. You shouldn’t need to add any more oil. Cook on a high heat for 2 mins then add the spinach with the lemon zest and remaining juice. Stir till the spinach is wilted.
Serve the trout fillets scattered with the rest of the dill, the roasted veg and the wilted spinach. Pour over the orange butter sauce.