Mirepoix is called the "holy trinity" in french food. It's just carrots, onions and celery. THATS IT. Seriously this shit is like el oh el ez mode. It's not exactly a "dish", but it can be used for many many things. Preparing this dish will develop chopping, stewing and soup skills. It could also be used to deglaze pans after cooking say pork chops and then after it thickens up you pour the mixture over the chops. YUMMO!!!
The whole point of this mixture is to bring an earthy taste to your dishes that lacks in different "nationalities" of dishes.
Dice all ingredients in decently uniform sizes. This isn't important for the taste, but it looks nice if you're cooking for others.
Use it in whatever application you want!!!
For stews, mix in a pot with some water. Congrats, you've made vegetable stew.
Take that stew and add a deboned chicken and congrats you've made chicken stew. (leave the fat and skin on for taste or remove them to make it healthier)
Note : In cajun cooking we have the same "trinity", but its onion, bellpepper and celery. Garlic, green onion and fresh parsley make fine additions to this mix. You can chop it all up and freeze it. -Booga