Cook the potatoes in a microwave on full power for 12 minutes, until cooked. Scoop out the inside of the potatoes into a bowl, mash with a fork and discard the skins.
Place the salmon on a plate, cover with clingfilm and microwave on full power for 3-4 minutes, until just cooked. Drain off any cooking liquid, add the fish to the potato and allow to cool.
Place the peas in a bowl and just cover with water. Cover with clingfilm and microwave on full power for 3-4 minutes. Drain.
Add the peas, mayonnaise, lemon zest and lemon juice to the potato and fish, mixing everything together well.
Season with freshly ground black pepper, shape into 8 fishcakes and dust with the flour.
Heat the oil in a pan and fry the fishcakes for 2-3 minutes on each side. Serve with salad.