What is the origin of the idiom "big enchilada" and when to use it?

The origin of the idiom "big enchilada" is believed to be rooted in Mexican food and culture, specifically referencing the enchilada, a popular Mexican dish. Enchiladas are tortillas filled with various ingredients, rolled up, and typically topped with sauce and cheese. The reference to the "big enchilada" may signify the largest, most important, or most substantial part of a meal, and this metaphor has been extended to describe a person in a position of significance. It is used in a colloquial or informal manner to refer to a person who holds a position of great importance, influence, or power.