Heat the oven to 200C (180C fan)/390F/gas 6. Put the trout fillets on a small lined baking tray, drizzle with half a tablespoon of olive oil, scatter over a pinch of sea salt and top each fillet with a slice of lemon. Bake for 12-15 minutes, until just cooked through. (If you have an air-fryer, the fish will take eight to 10 minutes.)
Meanwhile, bring a large pan of salted water to a boil, then cook the linguine according to the packet instructions, until just al dente. While the pasta is boiling, get all the remaining ingredients ready.
Drain the pasta in a colander, reserving a mugful of the cooking water. Return the empty pasta pan to the hob on a low heat, add the remaining two tablespoons of olive oil, then fry the garlic, chilli and lemon zest for just 30 seconds.
Add the grated courgette, fry for a minute, until just starting to soften, then add the drained pasta, dill, lemon juice and a teaspoon of salt. Stir well – there should be enough liquid from the courgette to form a clinging sauce; if not, add a tablespoon of the reserved pasta water. Flake the cooked trout in large pieces into the linguine, then stir gently to combine. Taste and adjust the salt as needed.
Use tongs to divide the pasta and trout evenly between two warmed bowls, top with the pine nuts and serve hot.