Kosher food laws are part of Judaism, from which Christianity grew.
But what Christian denominations or traditions follow, or historically have observed Kosher food laws?
The Ethiopian Orthodox Tewahedo Church maintains a practice that resembles Kosher food laws. (There are similarities and differences: the members of this church avoid pork, but they do commonly mix meat and dairy products in their cuisine.)
If by 'kosher' you mean biblically defined food that is clean / unclean in places like Leviticus 11, and not Talmud / Mishnah (Judisam); then the answer to your question 'Are there or have there been any Christian traditions that follow Kosher food laws?', is yes there are.
A few that come to mind are:
"Adventists are known for presenting a "health message" that recommends vegetarianism and advocate adherence to the kosher laws in Leviticus 11. The observance of which means, abstinence from pork, shellfish, and other animals proscribed as "unclean". " — Wikipedia
"The church strictly observed the Saturday Sabbath, annual festivals described in the twenty-third chapter of Leviticus, and strongly advocated the clean meats listed in Leviticus 11." — Wikipedia
"... we confidently call upon believers to distinguish between clean and unclean animals in their diet, for both spiritual and physical benefit" — Eating the Bible Way, A teaching booklet from the Church of God (Seventh Day)
"... includes belief in the impending Apocalypse followed by the millennial reign of Jesus Christ on Earth, along with Old Testament dietary provisions, tithing, observance of seventh-day Sabbath, bans on holidays and festivals with pagan roots like Christmas and Easter ..." — Wikipedia
I suspect a more thorough study would lead to the discovery of additional ones.
Hope this helps.