Half-fill a large saucepan with cold water and add a tiny pinch of salt. Place on a high heat and bring to the boil. Meanwhile… If using fresh peas, pod them into a bowl, then leave to one side. Use a Y-shaped peeler to peel the potatoes, then chop into 1cm chunks on a chopping board. Once the water is boiling, carefully add the potatoes, bring back to the boil, then turn the heat down to medium and simmer gently for around 10 minutes, or until cooked through, adding the peas for the last 2 minutes. Meanwhile… Finely chop the chives and add them to a mixing bowl. Drain the salmon in a sieve over the sink . Add the salmon to the bowl, using a fork to flake it into small chunks. Once cooked, drain the potatoes and peas in a colander over the sink then leave them to cool completely. Meanwhile… Use a microplane to finely grate the lemon zest, then add it to the bowl along with the flour. Crack in the egg and season with a tiny pinch of pepper. Once cool, tip the potatoes and peas back into the pan and use a potato masher to mash them really well. Add the mash to the bowl, then mix together until really well combined. Sprinkle a little flour over a clean work surface and onto a large plate. Divide the mixture into 8 and use your hands to pat and shape each ball into a fishcake, roughly 2cm thick. Place them onto the floured plate, dusting your hands and the top of each fish cake lightly with flour as you go. Place a large frying pan on a medium heat and add 1 tablespoon of olive oil. Carefully place the fishcakes into the pan and cook for 3 to 4 minutes on each side, or until crisp and golden, turning carefully with a fish slice. Cut the zested lemon into wedges. Serve the fishcakes with some seasonal green veg or a fresh green salad and lemon wedges for squeezing over.