Preheat the oven to 375 degrees Fahrenheit (190 degrees Celsius).
Slice the tops off of the tomatoes and scoop out the seeds and pulp, leaving a hollow shell. Set aside.
In a small pot, bring the vegetable broth to a boil. Add the quinoa, reduce the heat to low, cover, and simmer for 15 minutes.
In a medium mixing bowl, combine the cooked quinoa, minced garlic, diced onion, chopped herbs, olive oil, salt, and pepper.
Stuff each tomato with the quinoa and herb mixture, making sure they are filled to the top.
Place the stuffed tomatoes in a baking dish and bake for 30 minutes, or until the tomatoes are soft and the filling is lightly browned.
Serve hot as a side dish or add a protein for a main course.