In a medium saucepan, cover quinoa in water and allow it to soak for 5 minutes. Stir quinoa and pour into a strainer, rinse with cool water.
Dry the saucepan, then heat it over medium heat and add oil. When oil begins to shimmer, add carrot, onion, and celery and cook until tender, about 4 minutes.
Add quinoa and saute until the mixture emits a nutty aroma, about 1 minute. Pour in the broth and bring to a boil on high.
Reduce heat to low, add Italian seasoning then cover, and cook for 20 minutes until quinoa is tender and liquid is completely absorbed. Allow to sit covered for 5 minutes and then stir in the vinegar, salt, and pepper.