What are the trinity in French cooking?
Mirepoix (cuisine)
onions, celery and bell peppers
Similar flavour bases include the Italian soffritto, the Spanish sofrito, refogado/sufrito (braised onions, garlic and tomato) from Portuguese-speaking nations, the German suppengrün (leeks, carrots and celeriac), the Polish włoszczyzna (leeks, carrots, celery root and parsley root), the US Cajun / Creole holy trinity (onions, celery and bell peppers), and possibly the French duxelles (mushrooms and often onion or shallot and herbs, reduced to a paste).