Put the potatoes in a pan of cold water. Bring to the boil and simmer 30-35 minutes until cooked. Drain and steam-dry 2 minutes, then halve.
Heat oven to 200°C (fan 180°C / gas 6). Toss the potatoes, chorizo, onions, herbs, paprika and olive oil in a roasting tray. Season and roast 20 minutes, tossing halfway through.
Scatter over the peas, top with the salmon and season. Mist with cooking spray and roast 12-15 minutes until the fish is cooked through and flakes easily.