Most Jews- Conservative, Liberal, and Orthodox- avoid eating dairy and meat products together; depending on how strictly they wish to observe the Kashruth, some will have separate utensils. This all stems from three commandments found in the Torah:
רֵאשִׁ֗ית בִּכּוּרֵי֙ אַדְמָ֣תְךָ֔ תָּבִ֕יא בֵּ֖ית יְהוָ֣ה אֱלֹהֶ֑יךָ לֹֽא־תְבַשֵּׁ֥ל גְּדִ֖י בַּחֲלֵ֥ב אִמֹּֽו׃
The first of the first-fruits of your ground shall you bring [to] the house of YHWH your Deity; you shall not [boil?] a kid in the milk of its mother. Exodus 23:19
רֵאשִׁ֗ית בִּכּוּרֵי֙ אַדְמָ֣תְךָ֔ תָּבִ֕יא בֵּ֖ית יְהוָ֣ה אֱלֹהֶ֑יךָ לֹא־תְבַשֵּׁ֥ל גְּדִ֖י בַּחֲלֵ֥ב אִמֹּֽו׃
The first of the first-fruits of your ground shall you bring [to] the house of YHWH your Deity; you shall not [boil?] a kid in the milk of its mother. Exodus 34:26
לֹ֣א תֹאכְל֣וּ כָל־֠נְבֵלָה לַגֵּ֨ר אֲשֶׁר־בִּשְׁעָרֶ֜יךָ תִּתְּנֶ֣נָּה וַאֲכָלָ֗הּ אֹ֤ו מָכֹר֙ לְנָכְרִ֔י כִּ֣י עַ֤ם קָדֹושׁ֙ אַתָּ֔ה לַיהוָ֖ה אֱלֹהֶ֑יךָ לֹֽא־תְבַשֵּׁ֥ל גְּדִ֖י בַּחֲלֵ֥ב אִמֹּֽו׃
You shall not eat any carcass- to the ger which is in your gates you shall give it and he shall eat it, or sell it to a foreigner- for you are a sacred people to YHWH your Deity; you shall not [boil?] a kid in the milk of its mother. Deuteronomy 14:21
There is a running joke among Rabbinic Jews when commenting upon these verses; it goes something like:
G-d: And remember Moses, in the laws of keeping Kosher, never cook a calf in its mother’s milk. It is cruel.
Moses: Ohhhhhh! So you are saying we should never eat milk and meat together.
G-d: No, what I’m saying is, never cook a calf in its mother’s milk.
Moses: Oh, Lord forgive my ignorance! What you are really saying is we should wait six hours after eating meat to eat milk so the two are not in our stomachs.
G-d: No, Moses, what I’m saying is, never cook a calf in it’s mother’s milk!!!
Moses: Oh, Lord! Please don’t strike me down for my stupidity! What you mean is we should have a separate set of dishes for milk and a separate set for meat and if we make a mistake we have to bury that dish outside…
G-d: Moses, do whatever you want….
All jokes aside, when considering the context in which these verses are found, it is interesting to note that in all cases, they were no more than a verse before or in the same verse with the offering of the tithes and the first-fruits. Context should be the first priority in understanding difficult passages.
Rabbi Joseph ben Isaac, a 12th century Rabbi of Orlean, France, believed that the phrase as its classically understood is a mistranslation. In Bekhor Shor he wrote:
לפי הפשט, “בישול” לשון גידול וגמר, כמו “הבשילו אשכלותיה ענבים.” והכי קאמר: לא תניחנו לגדל ולגמול בחלב אמו, שתאחרנו עד שתגדלנו האם בחלבה, אלא בראשית תביאנו, דומיית תחילת הפסוק שאמר: “ראשית בכורי אדמת
According to the plain meaning, the term “bishul” here means grow or complete, as it is used [Gen. 40:10)]: “its clusters ripened (הבשילו) into grapes.” This is what the verse is saying: do not allow it to grow up and be weaned from its mothers milk. [In other words, do not] wait until [the kid]’s mother grows it with her milk, rather bring it at the beginning. This fits with the context of the first part of the verse, “the choice first fruit of the ground.” 
The verb was written תבשׁל and vocalized by the Masoretes as תְבַּשֵׁל – a pi’el, but could actually be vocalized as תַבְשֵׁל which is hiphil defective imperfect.
Most detractors of this interpretation point to Rabbi Isaac’s commentary on the same passage in Deuteronomy where he stated that the commandment was, indeed, concerning forbidden foods- completely reversing his former comment in Exodus. According to his opinion in the passage in Deuteronomy, it was in light of how the verse seemed to be connected with the preceding verses. However, on close examination, one can notice that this, again, is merely a traditional break provided by the Masoretes- who could have been moved by a traditional understanding of that verse in the 9th century when the Masoretic Text was prepared. In the MT, at the end of verse 21, there is an open space- which is signified by the Hebrew letter Peh and indicated the next verse began on a new line. This seemed to link the final clause with verse 21. The Masoretes were the ones who pointed the Text, and it was from them that the sof pasuq originated- meaning they decided where each verse began or ended . In both of the prior two passages, this clause was clearly written in the context of the bringing of the first fruits- in this context, the clause was the opening of the bringing of the tithes of the land. In light of this, it is a fair assumption that the Masoretes, as was their custom, followed traditional understanding and practices when preparing their Text.
According to Torah, the young only need be with the milk of its mother seven days before being offered-hardly enough time to be weaned.
שֹׁ֣ור אֹו־כֶ֤שֶׂב אֹו־עֵז֙ כִּ֣י יִוָּלֵ֔ד וְהָיָ֛ה שִׁבְעַ֥ת יָמִ֖ים תַּ֣חַת אִמֹּ֑ו וּמִיֹּ֤ום הַשְּׁמִינִי֙ וָהָ֔לְאָה יֵרָצֶ֕ה לְקָרְבַּ֥ן אִשֶּׁ֖ה לַיהוָֽה׃
When an ox, or lamb, or goat is born, and when it has been seven days under its mother, then from the eighth day and onward it is acceptable for an offering, a fire-offering to YHWH. Leviticus 22:27
The phrase לא תבשל גדי בחלב אמו might not have had anything to do with boiling or cooking- even less to do with eating. The verb B-SH-L carried a meaning of ripening; when considering how a plant ripens its fruit- by causing the fluid to cease flowing into it. The phrase could indicate a period in which the kid is brought to weaning from the mother’s milk. The meaning would be that at the time the firstborn are born, they were to be consecrated and handed over- weaned or not.
Consider the following
כִּֽי־לִפְנֵי קָצִיר כְּתָם־פֶּרַח וּבֹסֶר גֹּמֵל יִֽהְיֶה נִצָּה וְכָרַת הַזַּלְזַלִּים בַּמַּזְמֵרוֹת וְאֶת־הַנְּטִישׁוֹת הֵסִיר הֵתַֽז׃
For before the harvest, when the blossom is past, and the bud is ripening [gomeil] into young grapes, he shall both cut off the sprigs with pruning hooks, and take away and cut down the branches. Isaiah 18:5
וּבַגֶּפֶן שְׁלֹשָׁה שָֽׂרִיגִם וְהִוא כְפֹרַחַת עָֽלְתָה נִצָּהּ הִבְשִׁילוּ אַשְׁכְּלֹתֶיהָ עֲנָבִֽים׃
And in the vine were three branches; and it was as though it budded, and its blossoms shot forth [hivshilu]; and its clusters brought forth ripe grapes. Genesis40:10
In these two, speaking of plants coming to ripeness, there are verbs for weaning G-M-L and ripening B-Sh-L. The former is a pa’al active participle and the latter a hiphil perfect.
The shoresh carried the meaning of ripening as well as to boil. The piel- so it seemed- meant to boil, cook. The hiphil has a meaning of ripening. However, there are instances where the hiphil– written defective (with Tsere instead of the normal medial Yod)- resembled a pa’al or pi’el in the imperfect.
In every place the mitswah concerning the gedi appeared, it was in close relation- a pasuq before or after- to the giving of the bikhorim [first-fruits].
Concerning the giving of the bikhorim we are warned not to delay:
מְלֵאָתְךָ֥ וְדִמְעֲךָ֖ לֹ֣א תְאַחֵ֑ר בְּכֹ֥ור בָּנֶ֖יךָ תִּתֶּנ־לִּֽי׃ כֵּֽנ־תַּעֲשֶׂ֥ה לְשֹׁרְךָ֖ לְצֹאנֶ֑ךָ שִׁבְעַ֤ת יָמִים֙ יִהְיֶ֣ה עִמ־אִמֹּ֔ו בַּיֹּ֥ום הַשְּׁמִינִ֖י תִּתְּנֹו־לִֽי׃
There has been much discussion among the early 20th century scholars about the cache of Ugaritic tablets found at Ras Shamra and how they may lend new light to understanding vague verses of the Bible- among them is tablet UT52.14 (CTA23) in which was found a line which read- TBH.GD.BHLB
This phrase was rendered, Cook a kid in milk, by Virolleaud. Bible scholars jumped on board and declared that the Torah mitswah must have had something to do with ancient Canaanite religious practices. There are several objections which must be noted.
First: there is no mention of cooking or boiling as TBH, in Ugaritic, meant to slaughter.
Second: There is no mention of mother’s milk.
Third: the Ugaritic word divider appeared between the B and H of TBH which made any certain translation of the verb uncertain. Even if, as Virolleaud claimed, the verb is TBH, it would not mean to cook or boil. To base the meaning of the Torah’s mitswah on this partial evidence is premature- at best.
Fourth: the Ugaritic GD did not mean a kid [GDY in Hebrew]; this is the Semitic word for coriander which can be found in the Torah as well:
וְהַמָּ֕ן כִּזְרַע־גַּ֖ד ה֑וּא וְעֵינֹ֖ו כְּעֵ֥ין הַבְּדֹֽלַח׃
And the manna was like the seed of coriander [GD]; and its color was like the color of bdellium. Numbers 11:7
Lastly: Even if this was a pagan ritual, that in itself is not a sufficient reason to denounce the practice- all of the Israelite religious practices can be found in the pagan religious practices of the Near East; if the command was only to prohibit pagan practices, all forms would have been prohibited by Torah- this is not the case.
- Wegner, Paul D. The Journey from Texts to Translations: The Origin and Development of the Bible. Page 177. Baker Academic, 1999.