Below is what we wrote about the issue in Insights to Chulin 105a.

The custom to wait half an hour after milk is based on the Chumra of the Zohar. However, some question the Minhag (even though it is widespread), because the Zohar means either that one must not eat them not at the same Se'udah (as the Beis Yosef understands it), or that one must wait a full hour (as the Pri Chadash and others understand it). Where does the half hour Minhag come from? The author of Ma'adanei ha'Shulchan suggests that it is based on the opinion of Rabeinu Yonah in Berachos (21a of the pages of the Rif, as cited by the Magen Avraham OC 93:1), who says that whenever an "hour" is mentioned, it does not mean literally an hour, but rather a bit of time. The Ma'adanei ha'Shulchan also quotes Sefer Mateh Reuven (#186) who discusses the Minhag.,

Y. Shaw

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FROM INSIGHTS TO CHULIN 105a:

3) HALACHAH: HOW LONG DO WE WAIT TO EAT MEAT AFTER MILK

OPINIONS: Rav Chisda states that one who ate cheese is permitted to eat meat

right away and he does not have to wait. Is this the Halachah?

(a) The SHULCHAN ARUCH (YD 89:2) rules that one may eat meat immediately

after eating cheese, as long as he ensures that there are no particles of

cheese on his hands, as the Gemara earlier (104b) teaches. During the day,

one may examine his hands, but at night, when it is dark, he must wash his

hands before eating meat. In addition, one must do Kinu'ach and Hadachah

before eating meat (see above, Insight #1).

The TUR (cited by the SHACH #9) writes that even during the day, one must

wash his hands after eating a dairy food, because there might be some food

left on his hands that he does not notice. This is the common practice today

(LEVUSH).

The Shulchan Aruch adds that this applies only to eating *meat* (of an

animal) after cheese. One who wants to eat *poultry* after cheese may do so

without Kinu'ach and without washing his hands.

The RASHASH (Chulin 103a) writes that one who merely drinks a glass of milk

does not need to do both Kinu'ach and Hadachah. It suffices to do merely

Hadachah. This is also implied by the words of the RAMBAM (Hilchos

Ma'achalos Asuros 9:26), who writes that "one who ate cheese or milk" must

wash his hands and wash out his mouth before eating meat. When the Rambam

mentions "milk" is referring to a dairy *food* item, and not to a drink of

milk, because otherwise he would have discussed "one who ate cheese or

*drank* milk." This implies that one who drinks milk does not need to wash

out his mouth with Kinu'ach, and he does not have to wash his hands (if no

milk spilled on them).

(b) The REMA writes that there are those who are stringent to wait six hours

even after eating cheese before eating meat. This practice is based on the

words of the MAHARAM MI'ROTENBURG, cited by the MORDECHAI (8:687) and

HAGAHOS ASHIRI, who decreed upon himself not to eat meat after cheese until

six hours have passed, due to an incident in which he found cheese between

his teeth while eating a meat meal.

The Rema in DARCHEI TESHUVAH writes that this stringency applies only to

"hard" cheese (see Shach #15, Taz #4), and this is the way he rules in the

Shulchan Aruch. One who eats "soft" cheese and other dairy products may eat

meat right away, as long as he fulfills the necessary conditions (washing

his hands, Kinu'ach and Hadachah).

(c) As mentioned above (see previous Insight), some Poskim understand the

Zohar (Parshas Mishpatim, page 125a, cited by the BI'UR HA'GRA #6) to be

prohibiting eating meat immediately after cheese. The Zohar discusses the

severe punishment given to "any person who eats these foods (meat and milk)

together, or in the same hour, or at the same meal." The PRI TO'AR, PRI

CHADASH, and others understand that the Zohar means that it is prohibited to

eat meat within an hour of eating cheese.

However, the BEIS YOSEF (OC 173) quotes the Zohar, and says that some people

are stringent not to eat meat after cheese *at the same meal*, but rather to

end the dairy meal (with Birkas ha'Mazon or a Berachah Acharonah) and begin

a new meal. The Beis Yosef understands that the Zohar is not teaching that

one must wait an hour between cheese and meat, but rather that cheese and

meat may not be eaten at the same meal.