Let the seafood thaw. Then put in boiling salted water for 2-3 minutes. After cooking, rinse in cold water and drain well.
Mix the white wine vinegar, oil, garlic, parsley, sugar, the juice of about half a lemon and salt and pepper into a marinade, pour over the seafood and let it steep for at least 30 minutes (the longer the better).
When serving, half a lemon is enough for each person.