Why does everything start with an onion?

Onion, garlic, ginger, celery, carrot — cooked slowly in fat at the start, these build the low, savory foundation that everything else stands on. Nearly every cuisine on earth has its version: soffritto in Italy, mirepoix in France, the trinity in Louisiana, ginger-garlic in half of Asia.

The order matters because of surface area and sugar. Onions are sturdy — they want 5+ minutes to soften and sweeten. Garlic is small, thin, and sugary — it goes from perfect to bitter in about a minute. So: onion first, garlic near the end of the softening, spices bloomed in the fat right after. This one sequence prevents the most common beginner flavor disaster (burnt garlic) and unlocks the most common flavor upgrade (bloomed spices).

When a recipe 'starts with aromatics,' it's borrowing centuries of consensus that this is what makes food taste like someone cooked it.