Pat dry the tilapia fillet and wrap it in cling film. Place it for about 30 minutes in the freezer.
Take it out of the freezer and cut it into very thin slices. The slices should be as thin as possible. Freezing will help here, because the fillet is firm after freezing. It is important, that the slices are very thin.
Place the tilapia slices on a plate in a single layer and drizzle the lemon juice over the fish. Set aside.
Heat olive oil over medium heat (don't let it get too hot). Cook ginger, garlic, vanilla bean and rosemary sprig for about 5 minutes. Garlic, ginger should not turn brown.
Remove from heat and let cool slightly.
Add aceto balsamico, salt and pepper to taste to make a lukewarm vinaigrette.
Arrange the tilapia fillets on a serving platter and drizzle with the vinaigrette.
Top it with Parmesan and serve with some roasted bread.