1: Preheat the oven to 360°F (180°C). Prepare the salmon fillet: remove the skin and any remaining bones. Pour 4 tablespoons olive oil into an oven-proof dish. Turn the salmon in the oil twice to coat it with oil.
2: Squeeze the juice of ½ lemon over the fish. Salt and pepper lightly.
3: Slice 400 g cooked potatoes and arrange around the salmon. Scatter the chopped 30 g spring onion (scallion) and herbs of your choice evenly over the top. If necessary, trickle a little more olive oil over the potatoes.