The previous Daily Halacha resolved one issue with the aperitif, namely that of Beracha Aharona. Two other possible issues will be dealt with presently.
A second potential Halachic matter is that of “Beracha She’ena Tzricha”, an unnecessary blessing. The reason that one must be concerned about unnecessary blessings because one should not pronounce Hashem’s Name without a justified reason. In the case of the aperitif one recites blessings over the different foods that one is eating and then proceeds to do Netilat Yadaim, Hamotzi and have the meal. Since food eaten within the meal is exempted by Hamotzi, theoretically the foods eaten in the aperitif could have been eaten during the meal and would not require a blessing. By making blessings over these foods knowing one is about to have a meal, one may be making unnecessary blessings.
Several Poskim rule that on since there is an obligation to recite at least one hundred blessings on Shabbat, this overrides the concern of an unnecessary blessing, and indeed, the blessings over the aperitif are considered necessary. Rabbi Itzhak Hazan (Yehave Da’at, vol. II, § 22) quotes the HIDA (Birke Yosef, § 176:46) who says that whenever there is a need for a blessing, then Beracha She’ena Tzricha does not come into play.
The third issue is the concept of “Kiddush Bimkom Se’uda”. In order for Kiddush to be fulfilled, it needs to be accompanied by a meal. In other words,one does not fulfill Kiddush by simply reciting it and drinking some wine; it must be followed a meal and must be in the same place as the meal. In the case of the aperitif, especially one that lasts a while, there is a concern of violating Kiddush Bimkom Seuda when there is a such a long interruption between the Kiddush and the actual meal.
Rabbi David Ovadia (Nahagu Ha’am, Hilchot Shabbat, § 14) writes that it is not proper to engage in a lengthy aperitif as it may be a possible interruption between the Kiddush and the meal. Nevertheless, Rabbi Ben Zion Abba Shaul (Or LeZion, vol. II, ch. 20, § 25), discussing the custom of aperitif in Yemen, explains that, since the aperitif is eaten to enhance one’s appetite and is therefore necessary for the actual meal, it is not considered an interruption. Similarly, Rabbi Shlomo Zalman Auerbach (Minhat Shlomo, § 18) discuss the concept of Kiddush Bimkom Seuda during the Seder, in which a considerable amount of time passes between the Kiddush and the eating of the Matza. However, since one is involved in relating the Haggada, which is an integral part of the Seder, he explains that there is no concern of interrupting between Kiddush and the meal.
It should be noted that the Baba Sali was particular about observing the custom of aperitif. Although it was explained that one may eat more than a Kezait of aperitif and even foods which do not necessarily enhance one’s appetite, the Baba Sali was strict about eating less than a Kezait and about avoiding foods like fish.
Summary: There is a Halachic basis for the aperitif in light of the issues of Beracha Aharona, Beracha She’ena Tzricha and Kiddush Bimkom Seuda.