In earlier editions of Daily Halacha, we saw a distinction between bread and foods requiring "Boreh Nefashot" with regard to one who leaves in the middle of a meal. If one leaves after eating bread, before reciting Birkat Ha’mazon, he does not have to recite a new Beracha when he resumes eating. Since he is required to recite Birkat Ha’mazon in the place where he ate, this obligation "binds" him to his original location even after he leaves. By contrast, "Boreh Nefashot" does not have to be recited in the place where one ate, and thus after he leaves, he has disrupted his meal and must recite a new Beracha when he resumes eating, whether this occurs in his new location or when he returns to his original location.
The third category of food which needs to be discussed is food requiring "Me’en Shalosh" – meaning, foods which require one to recite "Al Ha’mihya" (such as cake and the like), or fruit from the seven special species, which require one to recite "Al Ha’etz" (such as grapes). "Me’en Shalosh" resembles Birkat Ha’mazon in that it must be recited in the place where one ate, and it thus stands to reason that if a person left before reciting "Me’en Shalosh," he does not have to recite a new Beracha ("Mezonot" or "Boreh Peri Ha’etz") when he resumes eating. His obligation to recite a Beracha Aharona in his original location "binds" him to that location, and therefore he does not have to recite a new Beracha if he wishes to resume eating. Although some Halachic authorities dispute this line of reasoning, we follow the famous rule of "Safek Berachot Le’hakel" (one does not recite a Beracha in situations of Halachic uncertainty), and thus no Beracha is recited in such a case. This is the view of the Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), as well as of Hacham Ovadia Yosef, in his work Halichot Olam.
It must be emphasized that one should avoid this situation and not leave before reciting a Beracha Aharona, as by doing so he puts himself in a situation of Halachic controversy. But if one did leave before reciting "Al Ha’mihya" or "Al Ha’etz," he does not recite a Beracha when he resumes eating.
If one left after eating less than a Ke’zayit of "Mezonot" food or fruit from the seven species, then he would have to recite a new Beracha before he resumes eating. Since he left before he became obligated to recite a Beracha Aharona, there is no obligation connecting him to his original location after he leaves, and thus he must recite a new Beracha.
These Halachot appear in Yalkut Yosef – Berachot, p. 81 (listen to audio recording for precise citation).
Summary: If a person ate a food requiring "Al Ha’mihya" or "Al Ha’etz," he should not leave before reciting the Beracha Aharona, but if he did, he does not recite a new Beracha before he resumes eating. If, however, he left before eating a Ke’zayit, then he must recite a new Beracha before he resumes eating.
