Important components:
QuoteMirepoix (pronunciation: meer-PWAH) is the aromatic flavor base made by lightly cooking onions, celery, and carrots. The vegetables are cooked slowly in butter or oil in order to coax out the flavors without browning or caramelizing them.
You will find a variant of this in most French, Italian, and Spanish cooking.
Other trios and bases:
Cajun Holy Trinity: onion, bell-pepper, celery
Spanish/Latin Sofrito: onions, garlic, tomato
German Suppengrün: leeks, carrots, celery
Chinese Trio: scallions, ginger, garlic
Indian Curry base: ginger, garlic, onion.
"Marry Me Chicken" base: garlic, sun-dried tomatoes, red pepper flakes.
Costco "F-It I married" Trio: Croissant, Brazi-Bite, Macaroon.
Costco "Good Behavior" Trio: sardines, olive oil, faith.
Safe Password Base: uppercase letter, cursive letter, number, haiku, hieroglyph, your first born sacrificed, blood of a virgin without Jesus as external stimulus.