Heat the olive oil in a large pot over medium-high heat. Add the onions and garlic and cook for 2 minutes. Add the carrots and celery and cook for another 5 minutes.
Add the thyme, vegetable broth, wild rice blend, salt (if using) and pepper to the pot. Bring to a boil, then reduce heat to low. Simmer for 45 minutes or until the rice is tender.