Place the seafood in a wide sieve or colander, defrost and drain. Peel and finely chop the onion. Prepare pasta in boiling salted water according to package instructions. Heat oil in a pan and sauté onion cubes for 2-3 minutes. First add the seafood and sweat briefly, then stir in the tomato paste.
After 2-3 minutes add the tomatoes and vegetable stock to the pan and simmer gently for about 5 minutes. Wash basil, dab dry and cut leaves from a stalk into thin strips. Season the sauce with salt, pepper, paprika and a little sugar. Finally add basil. Drain the noodles, serve with the sauce and garnish with basil leaves and chilli pepper