What Beracha does one recite over gefilte fish?
Of course, as we all know, over fish one generally recites the Beracha of She'hakol. Nevertheless, the question was raised as to whether gefilte fish might be different because it consists of flour or matza meal. The answer that is given involves a fundamental principle in the rules of Berachot: although generally we always consider flour to be the primary ingredient, such that foods containing flour require the Beracha of Mezonot, this applies only if the flour is added for the purpose of contributing taste or nourishment. When flour is added to a food purely to serve as a paste to hold the food together, then it is not perceived as the food's primary ingredient. And since the flour or matza meal in gefilte fish serves precisely this purpose to hold the pieces of fish together one recites over gefilte fish the Beracha of She'hakol, just as one does over fish generally.
With this principle in mind, let us turn our attention to the question of the Beracha to be recited over cheesecake. Cheesecake is generally made with a thin crust at the bottom. Should that crust be considered the primary ingredient, such that cheesecake would require Mezonot, or would cheesecake resemble gefilte fish in this respect, and warrant the recitation of She'hakol? Rabbi Shlomo Zalman Auerbach (Jerusalem, 1900-1995) ruled that since the crust clearly is not made for the purpose of keeping the cake together after all, the cheesecake would retain its consistency even without the crust it is, indeed, seen as the primary ingredient. Therefore, over cheesecake one recites the Beracha of Mezonot.
Summary: A food item containing flour generally requires the Beracha of Mezonot, unless the flour is added only for the purpose of consistency. Therefore, over gefilte fish one recites She'hakol, whereas over cheesecake one should recite Mezonot.
