Mirepoix works so well to flavor dishes because it offers a balance of aromatics from onions and celery and pairs them with the sweetness of carrots. ... Taking the cooking further to browning, or caramelizing, changes the flavor of the vegetables. Sweetness deepens and intensifies.

What is the purpose of mirepoix?

Mirepoix is a recipe base made from diced vegetables that are cooked slowly (usually with some sort of fat, like butter or oil) to sweeten and deepen the flavors of a dish. The mix is cooked over very low heat, as the intention is to intensify the vegetables flavor — not to caramelize them.

Why does the size of mirepoix matter?

They all cook at about the same rate, so if they're the same size they will cook more evenly. Here's a quick tip: if you're making a small mirepoix, you can make several cuts along the length of the celery to get a more similar size to the carrots and onions.