1. Preheat the olive oil in a Dutch oven over medium-high heat.
2. Once hot, add in the onion and sauté for 3 to 5 minutes, until tender, translucent, and fragrant.
3. Once the onions are sauteed, add in the vegetable broth, beets, potatoes, thyme sprigs, and bay leaf, and bring to a boil.
4. Once boiling, reduce the stove heat slightly and let simmer, uncovered, for 20 to 30 minutes.
5. Then, remove the bay leaf and the thyme sprigs.
6. Once those herbs are removed, puree the soup in a high-speed blender or with an immersion blender until smooth.
7. Once the soup is smooth and in the pot, add in the vinegar and stir everything together.
8. Once the soup is all combined, serve it up, and enjoy!