Q. I remember learning that there is an obligation to wash and eat a bread meal at least once a day during Rosh Chodesh. Why is it that not all do so?
A. Shulchan Aruch (419: 1) rules that it is a mitzva to be “marbeh,” enlarge and augment on the seuda of Rosh Chodesh. Mishna Berura (1) mentions that in principle one is not obliged to eat a seuda with bread that requires benching, as mentioned also in O.H. 188: 6). However, it is better if one does. He further adds (ibid. 2) that one should add a special dish to the regular meat eaten, for the honor of Rosh Chodesh, even on Shabbos.
However, Kaf Hachaim (ibid. 5) maintains that the seuda of Rosh Chodesh should be consumed similar to the seudos of Shabbos and Yom Tov. (See also Ben Ish Chai – Vyikra 2: 10, and Darkei Chaim Veshalom 489).
Tur (419) quotes the Pesik’ta’s saying that; ‘All the food to be given to one during the year, is pre-dictated on Rosh Hashana, excepting for what one consumes during Shabbos, Yom Tov, Rosh Chodesh and Chol Hamoed.’
Horav Shlomo Miler’s Shlit’a opinion is that although there is no obligation on a seuda for Rosh Chodesh, one should follow his established traditions and minhogim.
Rabbi A. Bartfeld as advised By Horav Shlomo Miller and Horav Aharon Miller Shlit’a