Cut herring fillets into bite-sized pieces.
Mix together sour cream, lemon juice, onion slices, peppercorns and salt. Pour the mixture over the herring and toss with a fork to coat all pieces. Refrigerate 3 hours at least, or until very cold.
Serve on a platter. Sprinkle with paprika. Garnish with sprigs of parsley and slices of lemon.