So far, we have seen that one is allowed to accept an invitation to a non-kosher house. The decision whether to accept or reject the invitation is in the hands of the guest, who should take into account the quality and future of the relationship, the level of trust he has in the host, and how knowledgeable is the host regarding the laws of kashrut. After those have been determined and the invitation accepted, the guest might worry about the kashrut of certain ingredients, the mode of preparation, and possible forbidden mixtures. As we review them one by one, please have in mind that my intention is not to give a final decision on each one, but rather provide the readers with information which will help them make their own decisions:
Kashrut of Dishes:
Traditionally we maintain separate sets for dairy and meat foods, for fear of cooking meat and dairy together, and because the flavor of one dish is absorbed in the pot, for example, and then transmitted to the next dish cooked in that pot. We will deal with the concern of mixtures later, but when visiting or traveling there is no need to worry about flavor absorbed in the dishes. As I explained in length in my article on Kashrut in the Modern Kitchen, the materials used for cookware, silverware, and surfaces are of very high quality and do not absorb any flavor. This rule applies also to dishes at a restaurant, hotel, Airbnb, catering business, etc. It also applies to chinaware, Corel, etc.
Dishes used on Shabbat:
The rabbis forbade food which was cooked on Shabbat and declared the dishes used to cook on Shabbat to be non-kosher. The prohibition of the food is not Halakah-based but a fine meant to deter people from doing it, and that Halakah is observed only if you know with certainty that the food was cooked on Shabbat. If you were invited on Shabbat and you have a good basis to believe that the food was cooked before Shabbat you are allowed to eat it. The non-kosher status of the dishes is dependent, just as dishes used for non-kosher food or for meat and dairy, on the absorption of flavor, and as explained above, it is not applicable nowadays.
Dipping dishes (tevilat kelim):
The practice of dipping dishes in a mikveh is rabbinic, and the poskim mention several cases in which one can be lenient and use the dishes without being dipped[1]. A guest can rely on this approach, and can even assume that the dishes were dipped.
Oven:
A large oven can be used for meat and dairy simultaneously as long as the dishes don’t splatter, and if the dishes are covered there is no concern at all. The oven deemed by Halakhic definition a large oven is much smaller than the average residential oven, and one therefore need not worry that the baked dish he is eating has absorbed flavor from the oven.
Mixtures:
The one mixture which can cause problems is that of meat and dairy (with the exception of Pesah and mixtures of Hametz). Part of the trust we have in the host is that he knows not to mix meat and dairy, so one should not be concerned that the host cooked meat with butter, but rather that he used, unknowingly, sauces or frozen foods with dairy ingredients. This is not a certain fact but a ספק – a doubt. The rule is that even if we assume that the host used a sauce with dairy ingredients, it will become null and void in the general mixture, and in any case, will not be a meat and dairy mixture which would be forbidden by biblical standards, only by later stringencies.
Ingredients:
Meat: if meat dishes are served (poultry, beef, mutton), one must rely on the host. If the host guarantees that the meat is kosher, and you feel you can trust him, there is no need, and there might be even a prohibition, to ask further questions. It does not matter if you regularly eat Glatt or Beth Yosef meat, you can eat at the host’s house, as I explained in my article about Glatt Meat.
Fish: if you can identify the fish as kosher fish (for example, salmon or trout), or if the fish is served with some skin on and scales are visible, it is kosher even if the host is not trustworthy. With other types of fish, such as tilapia which closely resembles catfish, one needs to rely on the host.
Dairy: there should be no concern about the host using, by mistake, non-kosher cheese, since all cheeses and dairy products are technically kosher. This is thoroughly explained in my article about Kosher cheese.
Vegetables and grains: the main concern regarding vegetables and grains is that they might be infested, but this concern applies only to what can be seen with the naked eye. The prohibition is only against a deliberate consumption of insects, and in most kitchens the regular method of preparation takes care of visible bugs. If one claims to not trust the cleaning done by the host, he should also avoid coleslaw, rice, broccoli, celery, chives and many other staples even under the strictest supervision. The rule of thumb, as Rabbi Yosef Mesas says and as explained in my article about the topic, is that the Torah was not given to angels and we do what is within our power.
Bread:
If the bread is home-baked, there is no need to assume that it was baked with butter or milk, which will render it dairy and unfit to be eaten with meat, or with lard, which will make it non-kosher. Most commercial breads do not contain dairy ingredients or lard. When buying fresh bread at a bakery, or wrapped bread at a store, one could ask about or check the package for ingredients. When the bread is served by the host, who generally do not keep kosher, there is a concern that he might not have bothered to find out whether the bread is dairy. The guest might choose not to eat bread, but since it is only a doubt and not certain knowledge, he is allowed to eat it, even with meat, because even if the bread were dairy, there is no forbidden mixture of meat and dairy.
Used oil:
If the host serves a dish which was deep-fried, you might want to ask him if the oil was used before to fry something else, which perhaps was non-kosher. The decision whether to ask depends on your assessment of the host and the possibility that he would unknowingly would do such a thing. If the host answers positively, it is better to avoid that food. You could decide not to ask and simply skip that dish, but if you decided to eat it, without asking, no prohibition was transgressed. The reason is that even if non-kosher food was fried in the oil and then it was used for frying kosher food, the amount of non-kosher flavor or fat which was absorbed in the oil and then transmitted to the second dish is negligible.
[1] שו”ת יביע אומר חלק ז, יורה דעה, ט:א: …וכן כתב המשנה ברורה בביאור הלכה (סי’ שכג סעיף ז) ד”ה מותר, שמן התורה אין שום איסור להשתמש בכלים בלא טבילה, ורק חכמים אסרו להשתמש בהם עד שיטבילם
