Heat your oven to 190°C/Fan 170°C/Gas 5. Scrub the potatoes. Halve or quarter them so they’re roughly the same size. Tip them into a pan. Cover with boiling water. Bring to the boil. Simmer for 5 mins. Drain.
Tip the potatoes into an ovenproof dish. Drizzle with 1 tbsp olive oil. Season with salt and pepper. Stir to coat in the oil. Roast for 30 mins.
Peel and halve the shallots. Trim the French beans. Add the shallots and green beans to the potatoes. Toss a few times to coat them in the oil and seasoning in the dish.
Nestle the salmon in the dish. Pop the dish back in the oven for 12-15 mins till the salmon is opaque and both the fish and veg are cooked through.
Slice the leaves off the radishes. Shred the leaves. Trim the radishes and halve or quarter any particularly large ones. Quarter the lemon. Finely chop the leaves from the dill sprigs.
Lift the salmon fillets out of the dish and pop them on warm plates. Stir the radishes and leaves into the potatoes. Squeeze over a little lemon juice.
Serve the salmon and roast veg scattered with the dill and with lemon wedges for squeezing.