Base Sauce of Carrots, Onions, Celery

Puzzle 14 of Fashion Throughout History Hard Pack

Question is: Base Sauce of Carrots, Onions, Celery

and the answer is: SOFFRITTO

Word Meaning:

SOFFRITTO — (cooking) A fried mixture of chopped onions, carrots and celery, used as the beginning point of a dish, especially in Italian cuisine; may also contain garlic, shallot, and leek.

Definitions from Wiktionary.