Generally, the Beracha of "Hamosi" that one recites over bread covers all food eaten subsequently as part of the meal. Therefore, after a person recites "Hamosi" at the beginning of his meal, he does not recite any Berachot over the other foods served as part of the meal.
The question arose concerning a wedding guest who was served as an hors d’oeuvre a small piece of bread with meat. The guest was aware of the Halacha that hand washing is not required before eating less than a Ke’zayit of bread, and so he recited "Hamosi" and ate the hors d’oeuvre, ensuring not to eat more than a Ke’zayit. Thereafter, other food was served, and he questioned whether he should recite Berachot over the new food. As mentioned, the Beracha of "Hamosi" generally covers foods eaten subsequently. In this case, however, the Beracha was recited over less than a Ke’zayit of bread, and so perhaps it cannot cover the subsequent foods.
Rabbi Moshe Halevi (Israel, 1961-2001) addresses this question in his work Birkat Hashem (vol. 3, p. 339), and rules that the Beracha of "Hamosi" indeed covers other foods even in such a case. He likens this situation to one where a person drinks a small amount of wine. According to the accepted Halacha, the Beracha of "Boreh Peri Ha’gefen" recited over wine covers all beverages drunk subsequently, regardless of the amount of wine drunk. Even if a person drinks just a small sip of wine, the Beracha recited over that sip covers all beverages he drinks subsequently. Similarly, Rabbi Moshe Halevi contended, the Beracha of "Hamosi" covers subsequent foods regardless of how much or how little bread a person ate.
Hacham Ovadia Yosef, however, in his work Yabia Omer (vol. 10, Orah Haim 17), disagrees, drawing a basic distinction between the cases of wine and bread. Based on the comments of a number of Rishonim (Medieval Halachic scholars), Hacham Ovadia asserts that the Beracha over bread covers other foods due to its function as the Beracha over the meal. We view the Beracha of "Hamosi" as not merely a Beracha over bread, but rather as a Beracha recited over the entire meal, and, as such, all foods included in the meal are covered by this Beracha. Accordingly, the Beracha of "Hamosi" covers other foods only when it serves as the Beracha over a meal. But in a case where a person eats less than a Ke’zayit of bread, the "Hamosi" clearly cannot be viewed as a Beracha over the meal, since less than a Ke’zayit of bread does not suffice to establish the formal status of a meal. Hence, in this case, one must recite Berachot over the foods served subsequently. This is also the view taken by Hacham Ovadia’s son, Hacham David Yosef, in his work Oserot Yosef (in the back of his Halacha Berura, vol. 9, Siman 3; listen to audio recording for precise citation).
Summary: The Beracha of "Ha’mosi" recited over bread covers all foods eaten subsequently as part of one’s meal, but only if he partook of a Ke’zayit or more of bread. If one recited the Beracha over less than this amount of bread, such as in the case of small hors d’oeuvres, then he must recite Berachot over the foods he eats subsequently.
