Is Filet Mignon Kosher?

This age old debate has turned into a battle of ashkenazi vs sephardic beliefs.

A cow is a cow is a cow

Cows are kosher according to the Torah. Therefor from a 30,000 foot view, Filet Mignon if kashered according to the specific process outlined in nikkur guidelines Filet Mignon, just like any other muscle of the cow can be deemed kosher.

What needs to be removed

The hindquarters by default carry more chelev (forbidden fats) and the removal of the Gidanasheh (sciatic nerve) is required. This requires meticulous attention to detail and skill in order to maintain the integrity and composition of the beef. 

Historical vs. modern times

Historically both sides of the Jewish aisle would conduct nikkur on the hindquarters in order to enjoy some of the most tender meat on the entire steer. However, in modern times the time, labor and cost associated with this process has pushed the ashkenazi kashrus movement to simply sell off hindquarters to their non-kosher partners. The sephardic kashrus movement have stayed committed to this process.