First, cook the linguine in 2.25 litres of boiling salted water for 8-10 mins (check on the pack) until al dente.
Meanwhile, heat the oil in a medium saucepan, add garlic and rosemary, stir them around and cook over a medium heat for a couple of mins before adding the vermouth and continuing to cook for another min.
After that, stir in the mixed frozen seafood and the drained clams and toss them around the pan for 2-3 mins, or until the prawns have turned pink and opaque on both sides.
Finally, pour in the sun-dried tomato sauce, season and stir to mix everything well. Simmer gently for 5 mins.
Drain the linguine in a colander and divide between two warmed serving dishes. Serve with the seafood sauce.