Fun history of corned beef and cabbage.
Beef is cheap in America (lots of land, lots of cows, so there’s such a thing as cheap cuts). So a lot of immigrants who could never afford beef in their home country now had access to beef.
(Example spaghetti and meatballs is an Italian-American invention).
Now Americans hated immigrants (plenty stilldo sadly) and hated anyone who wasn’t Protestant so you had segregation. So in New York the Irish Catholic area was next to the Jewish area. There was solidarity between American Irish and American Jewish immigrants. So Irish-Immigrants bought corned-beef from Jewish butchers.
(In Ireland, you may eat bacon or lamb for St Patrick’s Day, but lamb was (and is) expensive in America, and Irish Immigrants got their meat from Kosher butchers - no bacon).
Brisket is a cut of meat from the front of the cow. It’s a very tough cut of meat. The salting process (it’s like soaked in salt for over a week) and cooking for hours and hours (it’s an all day stew) makes it tender.
So corned beef and cabbage is a dish that evolved out of affordable ingredients (tough cut of beef, cabbage and carrots and potatoes are dirt cheap) and proximity to Jewish immigrants.
St. Patrick’s Day Celebrations as we know them now (parades and the like) were started in America by Irish-American immigrants. Because WASP Americans (white, Anglo Saxon, Protestants) hated Catholics and hated the Irish.
And for all immigrants there was a big push to assimilate (give kids English sounding names, forget your language, become Protestant). But people don’t give up religion easily, names and language maybe, but not God.
So still today you have Irish Catholics, Italian Catholics, Mexican Catholics, etc and even Americans who aren’t practicing Catholic or aren’t religious may view being raised Catholic as part of a cultural identity linked to their heretage (the same way someone who doesn’t practice Judaism is still Jewish, some difference since Judaism is a hereditary religion, but for immigrants in a country that hates Catholics, being Catholic, having that tradition was and is part of being an outsider to American, part of an identity those in power hated and tried to erase).
So holding giant Irish pride parade celebrating the Catholic patron Saint of Ireland was sort of a “fuck you” to anti-Catholic anti-Irish sentiment. A “fuck you” to the idea that being an American meant erasing your traditions and history and pretending to be a White Anglo Saxon Protestant.
Look at us being proudly Irish and still Catholic. Obnoxiously, visibly Catholic and acting ways that the puritanical Protestants hate.
So what was a family religious Holiday became a big, visible celebration of heretage and homeland (a shared identity). And since it’s a celebration immigrants splurged by buying a big cut of beef (beef is cheaper in America, but immigrants did not have a lot of money and meat is still more than vegetables, so any cut of beef was still a special occasion thing) and supported their Jewish neighbors who ran the butcher’s shop.
(also, since it’s a St’s Feast, Lent restrictions on meat and drinking alcohol didn’t count, so eat a lot of meat and drink).
St Patrick’s Day in the US has its own history, heretage and ties to religion (and persecution for that religion). Traditions are tied to that history. So Corned Beef and Cabbage may not be a thing in Ireland but it’s a part of Irish-American tradition, history and culture.
https://www.smithsonianmag.com/arts-culture/is-corned-beef-really-irish-2839144/