Place the peas in a colander and run them under cold water to defrost them.
Bring a 20cm or 8" saucepan of well-salted water to the boil. I use 1½ teaspoons of water in a pan this size.
Snip the chives and set aside.
Roughly chop the capers and anchovy fillets.
Heat a 30cm or 12" nonstick frying pan over medium-high heat.
Pour the cooking oil over the salmon fillet and season generously with salt, around ½ teaspoon.Place the fish skin side down in the frying pan and press down for 15-20 seconds to keep the skin in contact with the pan.Reduce the heat to medium and cook for 5-7 minutes on the skin side. Flip the salmon once it has had its time and give it 3-4 final minutes, then remove and rest for 2 minutes.
Add the pasta to the water as soon as you flip the salmon and cook as per instructions. It should take 5-6 minutes; if it takes longer, adjust the timing appropriately.
Return the salmon pan to medium-low heat, add the olive oil, capers and anchovies, then cook for 60 seconds.
Add the peas and cook for another 60 seconds.
Drain the pasta and add it to the peas and anchovies.
Remove the skin from the salmon and flake the flesh over the pasta, throw in the chives and vinegar and toss to coat and combine.
If you like crispy skin, slice it up and use it to garnish the dish.