Very difficult issue that I am not currently going to address: the questions of cultured meat. See Rabbi Daniel Nevin’s teshuvah pages 29-30

A. What is the status of something that looks like meat but is actually pareve -- may it be eaten with dairy?

כל מקום שאסרו חכמים - דבר המותר ואסרוהו מפני מראית העין שהרואהו חושדו בדבר עבירה:

Whenever the sages prohibited something because of 'marit ayin' [it is because] the person who sees him will suspect him of violating a transgression.

(א) ודומה לצמר אסרוהו מפני מראית העין עם הפשתן והאידנא משי מצוי בינינו והכל מכירים בו לפיכך אין בו משום מראית העין ומותר עם הצמר ועם הפשתן:

The rabbis forbade certain types of materials that looked like linen because of the concern of it being marit Ayin for Shatnez. ...However nowadays people recognize silk so it should no longer be an isuue of marit Ayin

(ג) ...הגה ונהגו לעשות חלב משקדים ומניחים בה בשר עוף הואיל ואינו רק מדרבנן אבל בשר בהמה יש להניח אצל החלב שקדים משום מראית העין כמו שנתבאר לעיל סי' ס"ו לענין דם:

(3) ...RAMA: We make milk from almonds and place bird meat in it, since [milk and bird meat] is only rabbinically [forbidden]. But with meat from a domesticated animal, place almonds next to the milk, so that people don't misunderstand.

  1. May non-dairy creamer and margarine be served at a meat meal?

    1. ​​​​​​​​​​​​​​​​​​​​​As long as the “non-dairy” creamer and the margarine actually are pareve, yes, they may be served at a meat meal.
    2. It is advisable to serve label the creamer/margarine as pareve with a sign or to serve it in its container to avoid the appearance of serving milk with meat.

  1. Similarly, may I serve an impossible burger cheese burger?

    1. Impossible burger is plant based. It is not actually meat.

    2. It is permitted to eat an impossible burger cheese burger.

    3. It is advisable to have some mechanism for making it clear that it is impossible burger and not meat.

B. What is the status of something that looks tref but is actually kosher -- may it be consumed?

ישב לו קוץ בפני עבודת כוכבים לא ישחה ויטלנה מפני שנראה כמשתחוה לעבודת כוכבים ואם אינו נראה מותר נתפזרו לו מעותיו בפני עבודת כוכבים לא ישחה ויטלם מפני שנראה כמשתחוה לעבודת כוכבים ואם אינו נראה מותר

וישתה מפני הסכנה מאי אינו נראה אילימא דלא מתחזי והאמר רב יהודה אמר רב כל מקום שאסרו חכמים מפני מראית העין אפילו בחדרי חדרים אסור אלא אימא אם אינו נראה כמשתחוה לעבודת כוכבים מותר

The baraita continues: If a thorn became imbedded in one’s foot while he was standing before an object of idol worship, he may not bend down and remove the thorn, because he appears to be bowing down to the object of idol worship; but if he is not seen, it is permitted. If one’s coins were scattered while he is before an object of idol worship, he may not bend down and pick them up, because he appears to be bowing down to the object of idol worship; but if he is not seen, it is permitted.

The Gemara asks: What does the baraita mean when it states: If he is not seen? If we say it means that he is not seen by others, doesn’t Rav Yehuda say that Rav says: Wherever the Sages prohibited an action due to the appearance of prohibition, it is prohibited even in the innermost chambers where no one will see it, as the Sages did not distinguish between different circumstances in such cases. Accordingly, the fact that he is not seen by anyone should make no difference with regard to whether or not the action is prohibited. Rather, say: If he is not seen as one who bows down to an object of idol worship, i.e., he turns his side or back to the idol, then it is permitted.

So it comes as a bit of a surprise that the O U will not be certifying Impossible Pork.

The largest and most influential certifier of kosher products in the world has declined to endorse Impossible Pork, even though nothing about its ingredients or preparation conflicts with Jewish dietary laws.

“The Impossible Pork, we didn’t give an ‘OU’ to it, not because it wasn’t kosher per se,” said Rabbi Menachem Genack, the CEO of the Orthodox Union’s kosher division. “It may indeed be completely in terms of its ingredients: If it’s completely plant-derived, it’s kosher. Just in terms of sensitivities to the consumer … it didn’t get it.”

For Jews who keep kosher, the Impossible Burger has allowed some food experiences that would otherwise be off-limits because of the prohibition in dietary law on mixing milk and meat. For the last five years, Jews and kosher restaurants have been able to serve up cheese-topped chili, greasy cheeseburgers, and that quintessential American diner pairing: a hamburger with a milkshake.

“The Impossible Burger itself is a huge, huge success and people really, really like it,” Genack said. “It’s a really excellent, excellent product in every respect.”

With the new product, Impossible Foods wanted to give that same experience to Jews and Muslims who do not eat pork, along with others who are seeking to avoid animal products or reduce their environmental impact.

But the organization certifies other products that might seem to conflict with Jewish dietary law, explaining on its website that “a fish sauce may display a picture of a non‐kosher fish, the OU may appear on artificial crab or pork, or there may be a recipe for a non‐kosher food item on the label.” It even certifies other products that aim to replicate the pork experience, such as Trader Joe’s “spicy porkless plant-based snack rinds.”

But ultimately agency officials decided that a product called “pork” just wouldn’t fly, Genack said.

“We of course discussed it with the company and they understood,” he said.

JTA

C. What is the status of something that appears hametz but isn’t -- may it be eaten on Passover?