Heat oil in a large pot or Dutch oven over medium high heat. Add in celery and onions, and cook for about 2 minutes.
Add in ground beef, and cook until meat is browned and cooked through, about 5 minutes.
Stir in garlic, parsley, thyme, cumin, and salt & pepper. Cook for another 1-2 minutes.
Add in lentils, carrots, and 4 cups of broth and stir well. Bring to a simmer, then turn heat to low, cover, and let simmer for 60 minutes. Lentils should become tender.
Now stir in quinoa and remaining cup of broth. Cover and cook for another 30-40 minutes, or until quinoa is completely cooked and tender.
Turn off heat and stir in balsamic vinegar. Season with additional salt and pepper as desired.