1. Thinly slice fish into 2-inch pieces. (This process works best if you have a fillet knife—if not, use a very sharp knife.) In a medium glass bowl, combine vinegar and sugar and stir until dissolved. Add fish, onion, ginger, peppercorns, bay leaf, lemons, lemon or lime juice, and salt to the vinegar mixture; stir to combine. Be sure the fish is fully covered—if not, add a bit more vinegar and stir again. Cover and refrigerate 8 hours.
2. Before serving, add a squeeze of lemon or lime juice, parsley, and salt to taste. Serve with crunchy crostini.
Recipe courtesy of www.mydeliciousblog.com