Onions are the base of so many dishes. It is an aromatic that spans food cultures around the globe. In French cooking, mirepoix is onion, carrot and celery. In Cajun cooking, the holy trinity is onion, green pepper and celery. In Mediterranean and Latin American cooking, sofrito is onion, garlic and tomato with many variations depending on what country you are in. All of these contain diced onion. Not only are onions flavorful, they are low in calories and high in vitamins and minerals.